Sorry my German is verry bad so I put it in English.
The problem you discribe is a common failure int this type camcorder the cause of the problem is most of the time Capacitors that lose their capacity.
My camcorder is also powering up for 2 sec's then the power turns off exept for the tape loader and the auto focus. You can insert a tape but tape transport isn't working. Nothing appears on screen or in the viewfinder. Only a short flash.
My VL-73SA has the same problem didn't fixed it yet cause I dont have a Schematic (Schalteplan) guy's at Sharp USA and Japan couldn't help me so if anybody here has it can you please contact me ? Got loads of VHS-C tapes here that i have to put on DVD
Greetings Dominic