Is ECM bad

You say the check engine light won't go out. Have you scanned the computer for codes? If not, then that is the first thing to do before replacing parts. If you have scanned the computer and used the codes to replace a part but the problem persists, then the issue may have been with the wiring and not the part.

When a computer gives you a code, it is NOT telling you the part is bad. It is only directing you to a circuit. The circuit includes the part, wiring, connectors, and power supply.