Lowrance LMS-337 fish finder sonar depth sounder repair

Repair of fish finder, depth sounder, sonar that won't power on, keeps blowing fuse. Tools I use - Soldering Quick 861DW hot air station Duratech TS-1640 solder iron Multimeter RMM760D - can be found under many name badges Microscope Luzky Zoom 3.5 - 90x simul-focus single boom stand trinocular stereo microscope Camera - Lucky Zoom HD 14MP Oscilloscopes Siglent SDS 1102CML 100MHz 2CH Philips PM 3305 35MHz 2CH Bench supply Powertech MP-3086 0-30V 3A