Tips for custom ROMs on your OnePlus 7T

I've been messing around with custom ROMs for my OnePlus 7T phone. I wanted to document a few tips and tricks I ended up using, because most of the web sites with information on this seem kind of skeezy.

My phone is a OnePlus 7T. I have no idea what other phones these steps will work on. Probably some other OnePlus phones, but I really don't know, sorry.

Securely installing OnePlus fastboot drivers

TLDR: with device manager showing the unknown entry, click Windows Update -> check for updates, then advanced, then optional updates.

Most of the steps start with using Android's platform tools to boot into fastboot/bootloader mode using adb reboot bootloader and then some series of commands using the fastboot tool. The problem I had is once booted into the bootloader, the fastboot tool wouldn't find any devices.

I'm on Windows 11, and in Device Manager I saw an entry for an unknown Android device with no driver. I searched online and found that you're supposed to install a special driver for it, but most web sites offered their own links for a driver and said stuff like turn off driver signing verification.

Let me be clear: do not turn off driver signing verification. You don't need to, to get this working.

When you've got Device Manager showing you a driver it doesn't know about, go into Windows Update and click to check for updates. Once the spinner is done, go into Advanced options, then scroll down and click on Optional Updates. Might have to expand the "driver updates" section. There should be an entry for the fastboot driver.

Unbricking your phone if you're stuck in fastboot mode

If you get into fastboot and something in your install fails, fear not, this phone has a built-in recovery mode, if you have the right tools on your PC. The right tools were ones I found on https://onepluscommunityserver.com/.

Inside the download package was a tool called "MsmDownloadTool V4.0.exe". You run this tool and (unfortunately) allow it admin privileges, although I seriously doubt it actually needs them to function.

Choose "other" on the first dialog.

To get your phone to show up in the list, do the following. The steps are important to do in the right order.

1. Unplug the phone from USB
2. Power off the phone
3. Press and hold Vol+ and Vol-. Keep holding them.
4. While still holding them, plug in USB. Keep holding them! This boots the phone into something called EDL. I think it means Emergency DownLoad.
5. Keep holding down those buttons! When the phone show up in the list in the MSM tool, click the Start button in the tool.
6. Once the tool starts successfully transferring stuff to the phone, whew, you can finally release Vol+ and Vol-

The reason you have to hold the buttons down so long is that EDL mode times out after several seconds if you release the buttons, so you have to wait until the tool is actually doing a transfer before it's safe to let go.

Getting out of EDL mode

If you need to get out of EDL mode, press and hold Vol- or Vol+ and Power for several seconds. The phone should boot back to fastboot or boot up fully.

Local upgrade after unbricking your device

The OnePlus community server only had a link to Android 10 or 11, not the latest Android 12, so my first step after unbricking was upgrading to the same version I'd had on my phone before I messed with it. The phone did start auto-updating but to some intermediate version, not the latest one that I wanted.

Luckily some kind soul randomly uploaded those OnePlus upgrade files somewhere. Wow.

You copy the zip file with that official upgrade to the root of your device's internal storage. Go into the device's software update settings. Pause or cancel any over-the-air update in progress. Then hit the gear button in the corner and choose local upgrade. It should let you pick the upgrade zip file.

Locking the boot loader

Everyone is confronted with having their device wiped when unlocking the boot loader at the start of the process. What I didn't realize is that locking it would also wipe my device. So my advice to you is after you get the new OS booting, lock the boot loader right away before you start customizing the device or installing stuff.

A Trip to Korea

we took a trip to south korea for 10 days with the family. we stayed in daegu, one of the largest cities. we visited some friends who helped show us around, and it was a great time. i've been to cities in the US and a bit in other parts of the world, but this one felt busier and more walkable than most i'd been to. for someone who has spent their entire life in rural or suburb living, it was a shock.

obviously i don't have full cultural context, but here are some observations. definitely these will be one-sided and incomplete. hope i don't say anything too dumb

we felt very safe there. combination of strict gun control and high amounts of cctv surveillance meant that even in a busy city, people seemed to walk freely even at night. i saw a *lot* of women walking alone at night. i passed them at night in the street--i being a man, an obvious foreigner, at that--and they didn't seem even slightly hesitant. that's freaking awesome

also because of the strict gun control, they sold toy assault rifles and stuff in stores. no red cap on the front to indicate it was a toy. if that's not telling you they're doing something right, i don't know what is

everything was *cheap*. most delicious bowl of ramen i've probably ever eaten? $7. entire meal of fresh meat and veggies and sides for 4 adults and 4 kids? like $70. big bag of chips? $2

because of how cheap it was, we ate at restaurants almost every day. got a huge variety of delicious food. every meal was awesome. one of my favorites was what my friends called a "beef 'n leaf". they give you raw meat and let you grill it at the table. then you get a bunch of different types of leaves, wrap the meat with sauces and other toppings in leaves and eat those. so freaking good.

people were universally polite, even with crowded streets and so on. very little yelling in public.

not a lot of car horns. contrast with Mumbai, which is nonstop car horns every second of the day

in the morning, old people are out and about and there are 90000 deliveries happening

in the night, say 9 pm or later, there are 90000 attractive young people doing night life

I walked with my buddy to a part of daegu we called the Overstimulation District (complimentary). that is where all those young people congregated. lots of restaurants and bars, also some shopping.

not a lot of diversity. yes obviously there are koreans with many different backgrounds and many invisible differences, but I saw almost nobody who wasn't korean. I felt the contrast starkly when i went to the store after coming back home and saw 50 wildly different ethnicities or backgrounds represented within my field of view

there were a *lot* of cute tiny trucks. the Porter II was very popular, as was some model that said "damas" on the side

motor scooters were extremely popular for deliveries. we saw them everywhere

almost all cars were black or white. not a lot of colorful cars

for that matter, the style of dress was mostly black, white, or other muted colors. not a lot of bright colors where we were

the style of dress was also a bit conservative. sleeveless tops for women were basically nonexistent

we rode the bullet train to busan and it was super cool. it was deathly silent on there, like a library. everyone sleeping or quietly working on their own thing. no loud talking at all. ridiculous. the train itself was also smooth as butter, quiet, and of course absurdly fast. similar experience to riding the taiwanese high speed rail from Taipei, which I was able to do several years ago

i was able to go clothes shopping for some baggy pants using a translator app for help. cool to be able to do that in another country

the weather was very hot, like 85-90 F the entire time, and more importantly like 80+% humidity the whole time. just absurd walking around and sweating that much for a week

everything there is decorated. taxi cabs have cute characters on the sides of them. random buildings have light-up parts. informational videos on the train had cute animations. most of it was purely decorative and not functional. i thought that was neat

Jimu Robot App for Android

TLDR: here is a link to download the Jimu Robot App for Android (jiami-jimu-official_website-develop-62.apk). I received this from the manufacturer when I emailed them. It's legit. I swear it doesn't have any viruses in it, at least not any that I put there. I've been using it at least for the building instructions, and it's paired with my Android tablet, though I haven't made it far enough through a build to check if it fully works for controlling it.

Read on for the rest of the background, if you care.

At a garage sale the other day my son spotted this Jimu Robot inventor kit for like 1/10 the normal price. I said sure, why not. It looked neat.

Problem is, it's Bluetooth-controlled through an Android app... and the app is no longer on the Google Play store, seemingly because the manufacturer has discontinued it or something. The app also has all the building instructions--no paper manual. So if I wanted to even build it without movement, I'd be out of luck.

So I did a bunch of web searching and found a million sketchy sites that surely would infect my computer with something, but nothing official. Finally, I found the email address of the company that used to make it, and I just emailed them (aftersales@ubtrobot.com). To my absolute shock, they emailed me a day later with a link to the APK. In case they somehow discontinue it even harder, there's a link at the beginning for the copy they sent me.