Ursa 4,6K stop working after firmware update fail

Hello everyone, I am very sad that my trusty Ursa Mini 4,6K (the 1st one, none Pro) seem to be dead since 2 hours now. I saw few hot pixels for the 1st time in 6 years and I decided to downgrade to an older firmawre (4.7) and then go back to the lastets just to see if there is any result for this hot pixel issue. Unfortunately, at the end of the downgrading process, the message on the computer was "update failed", (everythong was connected properly and plugged into AC). At this moment the camera was already switch off by itself. And since then no more possibility to switch on, on AC or battery, no noise, nothing
The only thing is whenI plug in to my computer with the camera utility opened it recognized the camera and say : please put the URSA ON to update, but of course it doesn't work.
If do you have any solution, idea, to bring back to life my camera I will be very grateful !
Thanks !

Update back to firmware 3.3 and it will immediately start working again

YES !!!!!!!!!!!!!!!!
It's ALIVE again !!! Yuhuuu, going back to 3.3 brings back the camera to life, Thank you very much Thibaud !
My hot pixels are still there, but the camera is usable, so that's fine so far !

Good to hear. Are you going to reinstall release 4.8?

Yes the 4.8 was installed without any issues. Everything is working perfectly well since. Thank you for your help!