Okay, update here. I had a moment of inspiration. The firmware files I tried to use were on a network share. Copying them to the update volume does not work. They have to be local. Once I copied them to the machine I was updating from, both the V0.2 and V0.3 firmware work fine.
I am sure that was a relief.
A few questions: Why did you want an old version?
For others, I opened the whats new of 0.3:
V0.3 20240620
1. Updated some English translations
2. Fixed some operational anomalies
V0.2 20240430
1. Updated some clocks that could not be saved after power off
V0.1 20240425
1. Updated the automatic shutdown issue