My 1994 Accord EX Vetch recently overheated. There was a split in the front of intake heater hose. I replaced the hose and the overheating stopped, but now the car almost never starts and sometimes stalls. I read that the main efi/pump relay may be the problem. I replaced that, but it didn't work. Do I need to replace the ECU? Or did the coolant leak cause some sensor/starter damage?
The car cranks strong, but won't fire up.

If the engine overheated badly, the aluminum head may have warped and the head gasket may now leak.

Would that cause it not to fire up at all?

Yes, the compression can be badly affected. Remove the spark plugs and test each cylinder's compression. It's not uncommon for valves to get damaged, too. This happened to my neighbor's Honda several weeks ago. They wanted $3,200 to repair everything. I helped with the repair, since this was too much money for her to come up with.