Power button repair

Power on while holding WRITE.
https://www.rolandus.com/assets/press_media_resources/Factory_Reset.pdf

The procedure for performing a Factory Reset is as follows:
1. Disconnect the power supply from the RP100 (AC Power) or unplug the guitar from the input
jack (battery power).
2. Press and hold the Select button while re-connecting the power or plugging your guitar into
the RP100's input.
3.When the display shows --, release the button and press then press the Store button. The
display will then read rEand the RP100 will reset to the original factory settings

To perform a factory reset on the Zoom R16 recorder, follow these steps:

1. Power off the Zoom R16 by pressing and holding the [STOP] button.
2. While holding down the [STOP] button, press and hold the [REWIND] button and the [PLAY] button.
3. Continue holding all three buttons for about 5 seconds until the display shows "Factory Reset."
4. Release all three buttons and the unit will automatically restart and restore all factory settings.

Note: Performing a factory reset will erase all user data and settings, so be sure to back up any important data before proceeding.

If it's anything like my radio (model below), pressing the power button repeatedly as you turn it on sets the "sleep" mode.
The number shown on the screen with each press it the number of minutes before it turns off. When it shows "on" it stays on indefinitely.

To turn it off you need to VERY quickly press the power button and get off it... If you hold the button it will stay on.

Weak batteries or power adapter would cause this.

The only "fix" for this is to replace the power switch. The internal latch has broken. I have seen this a few times. You can get the part from Pioneer directly. Contact them and request the power switch for your specific model. They may also request the serial number as there were a few variants of this model.

Dan

If you have a 12v power cord going to it i would try giving it a gentle wiggle. If you find a sweet spot and the keyboard stays on then you have a broken solder joint on the 12v input.

First thing is to check the power supply.

LIKELY you will find one of the voltages out of spec. You may need to check them with a scpe to verify they are pure DC.

At this age, electrolytic filter caps are very suspect and if power is dipping below the required the processor will continually reset or never run.

Sounds like a power supply problem. Likely have to go to a repair shop unless you are electronically capable.

I would expect either a cracked board or bad solder joint is causing the problem.