Screen failure: the system seems to reboot at the startup animation; this cycle is endless. However, the printer remains fully functional via the intranet interface. I just can no longer control it manually. Any ideas?
I could reach Stop Klipperscreen by UI but it had no visible effect even after hard rebooting. Screen still cycles on the graphic intro
Can you establish a SSH connection?
Like already mentioned from @cardoc, try to connect via SSH. You can also just grab a USB drive, copy the original update.deb on it, connect it to the Klippad and let it do a Softwareupdate. No data loss, no SSH.