Ok cable from the wall plate (Oh by the way I suggest an upgrade) goes to the roof. no farther. There is a connector in or on the roof (Mine is under a cover in the roof) and a 2nd cable from there goes to the antenna head.
Turn unit off (Light off) up on the roof disconnect cable from antenna CAREFULLY connect voltmeter red to center wire black to the "Sleeve" of the connector Be very careful not to short things out have partner turn on and see if you have full battery power.... I did not
The connector in the roof was ... basically history (Very corrorded)
Two new cable ends and a new double female (Barrel) connector. Some better sealant and I'm watching OTA as I type.
The amplifier almost (I STRESS ALMOST) Never fails it's in the antenna
THe wall plate upgrade Sensar PRO about 100 DIY install.