How to troubleshoot the xp5900
All I did was remove the back door, the battery, and put a firstnet SIM in it and a memory card. Since then, all I get is a blinking green light on charge. If I remove everything and the battery and put it on charge, it bootloops.
Sonim Customer Service is trash if you buy second hand.
Also - it appears nearly impossible to sideload any software that isn't a sonim product, be wary if you are buying a sonim handset but want to use it outside of sonims' ecosystem.
Is this a good question?