Today I copied the new bootimage to a new USB stick and replaced the original one. After restarting the NAS, the initialization and installation of TOS 7 began. Unfortunately, nothing happened after that; it's stuck in an endless installation loop, just like before. When I use the app, the initialization starts again every time, and I can no longer access the web interface. Now the NAS isn't working again, just like it was during the update from TOS 6 to TOS 7. It's really frustrating.
Update:
After the new boot image triggered a reboot loop with TOS 7, but kept restarting after installation, I reconnected the original USB drive to at least be able to use the NAS with TOS 6.
After booting from the original USB drive, the current TOS 7 was installed. Now 17 apps need to be updated, which is always very slow from the Terramaster servers in the evening, while everything runs very quickly in the morning. This has been the case all along, not just since the update.
NAS: f4-424 MAX | 64GB RAM Corsair Vengeance DDR5-4800 | 2x1TB Lexar NM790 | 2 x 4 TB + 2x 6TB Seagate IronWolf Raid1 |(Currently in (re)learning mode)