I'm talking diagnostics. No techy brain stuff involved. If you get the dreaded click, the first item in the chain to eliminate is the battery. As you can't load it with the starter, turn on all the lights and the heated windscreen if you have one: more than 9V - battery not the problem, on to the next item: relay, wires, connertors, solenoid, starter motor.
In this scenario, off-load voltage tells nothing
BRG Brooklands SV 2.0L Ammo Duratec 😬 It seems that perfection is achieved not when there is nothing more to add, but when there is nothing more to take away. (Antoine de Saint-Exupery)