Hello ,
I will be using my kemper in the near future for gigs.
I wonder what if all hell brakes loose and the kemper just fails to start or just quits.
Is there a plan/ checklist you can follow ?
Do we have users here who experienced troubles? If not, than the better 
But is there some magic button combo or usb stick repair...
Just wanted to be prepaired
First off I would suggest that you have a usb stick with a backup of your kemper near - I always keep one in the rack of mine.
I never had the case that my unit "quitted" and I wasn't able to use it anymore for the gig. Maybe 2 or 3 times (in 3 years extensive use) I had the unit become unresponsive to control inputs from the remote, but that was quickly resolved by rebooting.
However, If you want to be on the safest side, look for a small footprint backup rig like a helix stomp or even a strymon iridium.
Hope that helps
Apart from a MIDI (I use a MIDI controller) related DSP error (a long time ago - reboot fixed) I haven't had a problem and that includes gigging with Betas. If you are a part of the world where the quality of the mains supply is in doubt, use a power conditioner. (It's fine here in the UK)
This page may be of use: https://www.soundside.de/support/KPARecovery.htm
As above, I have a usb stick velcro'd to the back of my (Kemper!) head
Most of all - don't assume it's the Kemper thats at fault! there are many things between your hands and the sound that you hear (or don't hear)
e.g. Gtr vol off ... dodgy lead ... plugged into headphone socket ... loop activated (not the looper) but nothing plugged in the loop (my favourite!) ... volume pedal (wherever it is) set to off ... on a power head/rack - power amp not turned on ... speaker cable dodgy/not connected ...
Try and shut down properly before the 'grunts' pull the power - this gives the KPA the time to do it's housekeeping!
Get a decent case for it - its worth looking after
The Little Green Monster has been extremely reliable for me (famous last words!)
Skål
Andy
