HELP: my Boox keeps on rebooting!

Hi there,
I’ve been a Boox Nova pro user for a few days now, and today I have to face a serious issue:
each time I try to do anything, like creating a new Note, or open an Epub to read, my Nova Pro is rebooting, so I can’t do anything.
Firmware version is 2.2.1.
I tried to update to 2.2.2, but the installation failed, so I don’t know what to do exactly…
Thank you very much for your help !

Can you plug and charge the device and make the followinf test in the same time ?
What’s happen when you disable Wifi and Bluethouth ?
Could you remove all applications (APK) that you have installed ?
Can you try a full reset ?