OnePlus 6 with Custom ROM struggling to boot

[mr cheese]

Aight so this is probably not the place for this question but for the life of me I cannot figure out the social norms of asking questions on XDA forums so I'd figure I'd test the waters here to see if anyone could help me out.

 

I got a OnePlus 6 from a friend and wanted to go for some other ROMs since OxygenOS wasn't quite it for me for nighttime use. Unfortunately this has led to nothing but massive headaches trying to deal with this phone.

 

So far I've only gotten one ROM to work: AOSiP on Android 9 (which granted is a great ROM so I'm not complaining). Others, like Pixel Experience (Android 10) and Syberia (Android 9/10) have completely and utterly failed to boot. I just need some help troubleshooting my steps to see if I can get those other ROMs working.

 

For AOSiP the process was relatively simple and runs well

The two aforementioned distros had similar install process that just didn't work, no matter what I tried. I'll outline them here:

[All flashing was done via adb sideload from Xubuntu 18.04 on a laptop from like 2005]

1. Boot blu_spark TWRP [I used 3.3.1.x v109]
2. Flash OxygenOS 9.09 full then flash TWRP [OOS from the official OnePlus Website
3. Reboot and repeat to fill the other slot
4. Flash ROM, clear caches, flash TWRP
5. Reboot
6. Install GApps, clear caches
7. Reboot

I followed these same steps verbatim repeatedly. About 5 times per distro per version. The flash works just fine for OOS, and goes to both slots, and can even be booted from once finished. However, after flashing the custom ROM, the device will simply hang on the bootloader warning screen and never boot or make any responses whatsoever. Alternatively, it will attempt a boot, then reboot to recovery. This is repeated even after:

• Not flashing GApps
• Flashing Magisk
• Wiping /data and /sdcard
• formatting data
• flashing the ROM to the other slot

I've run out of ideas on how to fix this and I'm unsure why it's only affecting my device. Any advice? If any further details are needed please do let me know