ABS cracks after the oils leave the plastic.
ABS is good for about 15-20 years
Sears hasn't sold an ABS gamefisher boat for almost 50 years
You can try to smear goo on it, however the plastic will just break next to the patch
The scariest ride ever was a Hydro-stream V-king with a 225 on back. When you have to slow down to 80 to turn, you pull the upholstery with your sphincter
The 150 on a 15' would just be fun
take a volt meter. check for voltage on the blue wire feeding the relay. if power is there, its coming from the switch. if no power, check for voltage on the heavy blue wire coming from the relay to the motor. if power is there, its the relay.
then it should be easy to determine where the voltage is coming from. you are limited to the blue wire side of the controls. either your switch is bad and shorted, or your relay is bad and shorted.
most stringers have a hose connection at the trunion cap.
however if the drive is off, just connect the garden hose to the thermostat housing where the line from the transom comes in.
150 psi is a new engine
to me personally, 120 psi is where I start looking for a rebuild
however your gauge may be off. what was the spread of the compression numbers? you want only 10% variance