speaking as a dad :yayyy: .... and as an ex-mechanic :assim: ..... and as an ex-kid :jest: IMHO you gotta take ownership of your bike back!!!! Like fitting indicators is not really a big deal. But all mechanicking involves guess work &*****-up :knkknk: .
SO if you did it yourself you would know that maybe you might disconnect the battery "just to be safe".
However with modern 'clever' vehicles if the measured 'power rail' voltage drops too low for too long the ECU goes into 'safe' mode. On Triumphs iif you did that the 'engine' light comes on and stay son for three "heat cyles" (cold to hot to cold {and yes it gets hot 110 degrees C = 10% above boiling point}).
so I guess your dad was being very careful and the 'clever' electronics got pissed off with that. Bit like windows XP??????
Jon