i9300 odd behaviour: Replicant 4.2 working, Replicant 6.0 stuck in early bootloop
today I received an SIII (i9300) with CyanogenMod preinstalled (obvs. an old version, but working fine). I successfully installed the Replicant 6.0 recovery and sideloaded the 6.0 0003 image, but the device is now stuck in an early bootloop. The Samsung Galaxy SIII screen appears for ~15 seconds, then it goes to black for a couple of seconds, then Samsung screen again. No Replicant logo. Afterwards, I tested various other images:
- Replicant 6.0 0003
- twrp 3.2.3 + LineageOS 14.1 (20191115)
- twrp 3.2.3 + LineageOS 16.0 (20190710)
- Replicant 4.2 0004
- twrp 3.2.3 + CyanogenMod 11 (20160115)
This behaviour is stable and seems to be systematic. Old stuff works, newer images fail to boot very early, no Replicant/LineageOS screens appear. The baseband version is I9300XXUGNA8, which is probably not the issue, as I have multiple other i9300s with the same version and they run everything perfectly.
What could be the issue, faulty partition layout or something? Do I need to update another hidden(?) firmware to make newer images work? I could provide logs etc., but I don't know where to start. I know how to use the terminal and adb, so I could run some commands and post the output here.