sorry i have`nt reade every post but it sounds like the soliniod on the starter is knackered

very common problem on the turbo as the starter is the same on all cvh engine but the turbo exposes it to extremem heat which turn gunk to a paste then it just jams try

give the starter motor a good whack

bump toe start

all so jump it you may be reading 12 v which is nopt perfect but enough but you muight be low on amps which is the juice that kicks it over

Tony