Is this device registered with TRCSL?

No, as long as you charge up to 80% and stop.

Seems moisture is the culprit. Keep the phone inside a container with silica gel or rice overnight and see if the problem is resolved.

Connect the phone via USB to a PC or laptop ans select File transfer mode. Copy DCIM, documents, downloads, music and SmartSwitch folder (if using Samsung Switch).You can also use the Samsung Smart Switch Windows app to backup the phone to the laptop...

I understand. Before you hand the device for repair, make a full backup of the data to your PC/laptop and erase all the data. This way, you don't have to be worried about data theft.