If the transceiver doesn’t start at all, even with a fully charged battery, than most probably the fuse is blown up. In this case it is easy to change it. This is a so called Picofuse 2.5 [A]. They can be found at Conrad under reference number 529754
It’s externally accessible. You just need a spare fuse and a small soldering iron.
Internal short circuit
If changing the fuse doesn’t solve the problem, and the next fuse does blow up immediately when the rig is powered on, than probably there is something wrong inside the transceiver. To open the transceiver you need a Torx screw-driver T8. Unscrew as well the whole module inside and have a look aside, where the big electrolytic capacitor is located. The capacitor’s positive lead may touch the quartz situated on the PCB above. Reform the lead, in order to create a gap between the two components.