一加官网

https://www.oneplus.com/uk/support/softwareupgrade/details?code=PM1574156097213&awc=10855_1599071166_401d1c3d80fd805ca32cb1f10bdc342d&utm_source=aw&utm_medium=affiliate&utm_campaign=Sub+Networks&utm_term=78888&utm_content=0

Colt OS

https://forum.xda-developers.com/oneplus-3/oneplus-3—3t-cross-device-development/rom-colt-enigma-android10-v5-0-t3971691

Lineage OS 17.0

https://forum.xda-developers.com/oneplus-3/oneplus-3—3t-cross-device-development/rom-lineageos-17-0-oneplus-3-3t-t3990061

MSM Xtended

https://forum.xda-developers.com/oneplus-3/oneplus-3—3t-cross-device-development/cardinal-aosp-5-0-android-8-0-pre-t3693585

Nitrogen OS

https://forum.xda-developers.com/oneplus-3/oneplus-3—3t-cross-device-development/rom-nitrogen-os-beta-t3737654

下载速度暂无更好办法

升级氧OS安卓9要上锁fastboot

https://zhuanlan.zhihu.com/p/63810839

可以按照这篇教程，或者直接恢复出厂设置（经过测试没有用）