Deore hydraulic disc brake stuck in the open position

Pep

The Piston of my Shimano Deore hydraulic brake got stuck in the open position.
Both front and rear.
I dismounted the caliper and tried to clean them with tissue and oil, did not help, then again with alcohol, did not help, Then I left it overnight immersed in oil. Still stuck, even by pressing it with a flat head screwdriver no way to move it.
I cannot even clean the side surface of the Piston because it's completely inside the drum.

Out of desperation I just bought a new hydraulic brake set (the whole set: caliper, cable, Level, should be already bled), 60euro.

I was even tempted to move to mechanical disc brake, apparently not as strong braking power but should be easier to service, just not sure I could have found any mechanical disc brake compatible with my present rotor, changing also the rotors seemed wasting too much cash.

Perhaps I should have bled it?

Any advice?

Thanks,

Pep

Just to add:
if I press the lever I feel very little resistance, absolutely zero movement of the of the Pistons.
Sounds like air leaked inside the cable, right?

Disc sets about 8yr old, and 40-50k miles.
Pistons got stuck a few times before but I always managed to clean them and make them working again. This problem has been reoccuring increasingly more often.

The Rookie

How were you going to push the piston out with no pressure? I suspect the callipers are fine and you need to fix root cause.

It's a hose not a cable and it should be filled with mineral oil not air, so no, no air should leak out.

Sounds like they need a bleed.

No need to change the disc if going to mechanical callipers, not sure why you thought you would need to?

Pep

I learn now I should have serviced the caliper regularly (never bothered). I do service the chain and the pads very regularly.

https://www.youtube.com/watch?v=swwA2PwCIAw

Yes, YouTube is fantastic for learning bike repair. And ParkTool stuff, both videos and tools, are probably the best.