Your problem is likely coming from the dtbImage file. All of the testing I have done was done on Evilnat's dtbImage which you can find here https://github.com/Evilnat/xai_plugin/tree/main/Petitboot. Which firmware are you using?
I've had these same glod symptoms on multiple systems, considering the amount of improper shutdowns it's safe to say this system ran way longer than it says it did. It is most likely a bad gpu in the case of a 90nm gpu.
I installed petitboot on my 4.90 evilnat cechg04 and after going through 15 kernel panics in petitboot, i finally managed to run the hdd region script, but it only allocated 256mb to the partition, any way to fix that to have the full 22GB?