Keyboard on Privia will not energize

MOVs do not have a reset button.

Your AC adapter actually should have a fuse inside it to meet EU safety and CE safety requirments. Getting that apart is the challenge.

Test it with a voltmeter first.

If there is voltage, check to make sure the coaxial connector center post is the right size for the plug. If it is, you will need to open the cabinet. There might be a fuse present because of the battery option, in which case that fuse may be failed, a resistor in close vicinity may have failed as well. A broken wire or solder track would be more likely.

If no voltage output from supply, 2 ways to gain entry into a glued wall wart are not the prettiest, but it gets you into them. It saves buying a new one. One is to use a knife carefully and slice through the plastic at the seam where the 2 shells come together, it takes a while. The other method is brutish and quick- a side cutter/diagonal cutter on the corners is usually enough to break them on the seam.

Then check the fuse itself for continuity. If the fuse checks okay, carefully set it so you can apply power to it and check the rectifiers to see if any burned out- you want to essentially check the unit to see if the rectifiers simply failed.If it is a transformer supply, measure at the point where the transformer leads join the bridge rectifier quad. If there is AC present, the rectifiers failed. If there is no voltage/currnet- just check for voltage- the transformer burned out. If the unit is a switch mode type supply, check the rectifiers with an ohm meter with no power applied from the mains. You may or may not see any visigly failing capacitors- if you do those can be replaced, or you can simply replace the supply. This latter type might be held together with screws- it will certainly have less heft to it.