just because it shiny and new does not mean it's working ( could be a Chinese interment camp rebelling against the lose of body organs )

TRY https://www.scparts.co.uk/en/land-rover/land-rover-90-110-and-defender-1983-2006/body-panels/vehicle-cab-back-panel-and-floor-panels/

try ORA https://www.repco.com.au/parts-service/driveline/centre-bearings/ora-free-wheeling-hub-suits-hzj105-78-79-series-ora-901s/p/A8784119

try

try your pocket then we will all be safer

as the screen leaked check headers for water and corrosion the head un plugs to check them but care is required when re-inserting

have you checked the relays and header for water ingress

check the lighting switch for feed to front side lamps ( 7) as the terminal may have become detached as the front and rear are on different terminals

you will find that when you strip it the chassis will collapse in the centre so be careful how you support it my series 1 chassis ended up in the pile shown and the rest in the vacuum cleaner

try

have you checked fuse 13 engine compartment,fuse 21 passengers compartment

try

similar

three fuse wow my series 1 had just one fuse but now 20 ( not all used )and relays

sound like you have the wrong switch if terminal 2 loses ignition feed when cranking

may be relevant

have you checked the earth lugs on the instrument cluster

have you checked the relay base for good contacts as they us captured spade connectors and the contact area is very small and they have a tendency of being pushed back in the holder .the relay you have are they a well known manufacture and check to see if they are diode or resistor types

TAP ANTICLOCKWISE

just put both cable lugs on one stud until you sort the problem