disco td5 not start

ok so my bro in law td5 not start
no sing of pump running
when turns key on engain temp gose all way up and then back down even when cold
after that hill desent lights stop on

it will turn over ok but not start unlocks fine and the red flashing lights gose of
fule pump runs fine when 12v is put to it
put new realys in stilll not start

anyone may no whats up thanks

No idea really apart from plugging it into a nanocom, hawkeye or testbook & seeing what fault codes come up.

sorry for got to say when a testbook is used it says data erro and not read the ecu
it all started with the starter motor not wanting to work so he took some of the eath straps of and cleaned them up as well as the plugs for the ecu to make sure there was no oil in them
now the starter motor working fine but no fule pump / lights are on/not start like i said in first post thanks

rule out the inertia switch and if he messed with earths make sure the body is well earthed