Posting for a friend, not my car. Car is a 1994 gsr, mods are I/h/e 12.1:1 comp build and skunk2 ecu. He put in thermostat and fan switch last week. Ever since then car has been over heating. Tested thermostat, it's good. Today he replaced the spark plugs and also the lower radiator hose. Didn't touch anything else. Now it will not start. It cranks intermittently, pops, and makes a very weird grinding noise. Starter is good, tested it myself. Any ideas? Thanks in advance

 

Did he put the ground back on where the thermostat is when he replaced it?