My corrado tdi swap. In need of help!!!!!

So as it states I've swapped a 1998 Volkswagen Jetta TDI engine And wiring harness into my 1990 Volkswagen Corrado. I've Since ran into a few issues.one was the cluster I had nothing showing up. I read that I had to jump D8 to E2. once I did that I hooked up the battery and everything showed up on The cluster.couple hours later after doing another car I had to work on I went back to the corrado hooked back up the battery and the only thing coming on now was the Glow plugs, and also the odometer And the clock fade away when i turn on the key. Any ideas where to start to Look from here.

Clean the ground and positive battery connections.

so I checked in re check my ground and clean them thoroughly. But got nothing the car still has the coaster going out when the key is turned on

Use the schematic and verify each ground and positive connection to the cluster had what it needs.