Broken icons on touchscreen
This is not a Repetier-Server error. Our analysis shows that the uBlock Origin Extension in chromium is broken somehow. It adds 100% load and does not resolve.
As a solution you can simply delete this extension. Login over ssh and send:
rm -r /home/pi/.config/chromium/Default/Extensions/cjpalhdlnbpafiamejdnhcphjbkeiagm sudo reboot
After restart the icons and all functions should be back as it used to be.