My first tool choice is a 12 volt automotive test light
Brigth = Good
Dark = bad
Dim also bad
Problem exists between Bright and Not Bright
Start with clip any non-painted metal part near battery tip to battery Positive Bright good. Move out along the positive wire to the other end of the wire connected to the battery... Same test. .NOTE.. when you move the ground clip. if possible re-test the last known good spot (Testing ground)
No light on the first test move ground clip to battery - If bright bad ground cable
You come to a box with 2 bolts and wires attached. test all HEAVY wires if there are both heavy and small wires that is your cut off solenoid.
Home was where I park it. but alas the.
2005 Damon Intruder 377 Alas declared a total loss
after a semi "nicked" it. Still have the radios
Kenwood TS-2000, ICOM ID-5100, ID-51A+2, ID-880 REF030C most times