I think you didn´t do some steps which you should. The procedure shoul be on the first page. My procedure is a bit different but for me work for this days so it should help for you too.It sounds so easy, and - in fact - I had this rom installed pretty recently, then tried another rom - with disastrous results... bricked my RN8T but after many tries, was able to revive the phone with EDL (test points method) and QFIL. Meanwhile, I had bought a Redmi Note 11 as replacement (and placed my sim-card ex-RN8T into my new phone).
Well, I thought, now I'm going to use my old RN8T to try LineageOS 18.1 more specifically. Tried to install again, but this time the installation went wrong. All looked well until reboot: the animated LineageOS showed all right, but then the phone restarted again. And this repeated continuously.
I now have a question, because - in my opinion - thit is the only difference with the earlier installation when all went all right: does it make a difference whether a sim-card is placed or not?
With an older phone, some years ago, I was used to use TWRP to install the ROMs, having placed
the relevant zip-files on the phone beforehand. But this no longer appears to work, because - after wiping - everything on the phone seems encrypted (or has been decrypted after having been encrypted before the wiping). Therefore, I have to revert to flashing through adb sideload. And then something like "system destroyed" occurs. In other words, I'm doing something wrong. Is there somewhere a guide to install custom ROMs, writting in a somewhat more detailed way? Its sounds so easy: "flash recovery", "flash firmware", "flash ROM" etc., but in practice I ran into a bricked device. Happily, I've been able to bring back my RN8T to life so far, but it's a time-consuming process anyway. Still I would like to try a custom ROM, mostly for reasons of security. The RN8T will no longer receive updates; date of the last security patch is 1-5-2022. I woukl like to extend the life of the phone a few more years.
- Download the latest build and gapps
- Reboot to recovery
- backup data (if you are using LineageOS on same version and want use apk you have already instaled after flashing rom you are going update)
- wipe parttitons (system, data, cache, dalvik/ART cache, vendor, internal storage (backup all data you want save before do this)
- Format data (IMPORTANT DO THIS - cause reboots)
- Flash the latest build, disable_Dm-Verity_ForceEnrypt (optional for not encryption storage), last firmware and gapps
- after bootup directly reboot to recovery
- restare data (optional if you don´t wanto restore previous data you can set all data (install apk) just as new device
This way it should work for you. No SIM card needed.