Kurzweil PC3LE6 doesn't boot. Can't access boot loader


I have a Kurzweil PC3LE6 that doesn’t boot anymore.
When I turn on the power, every button, LED, pad and the screen lighten up, and nothing more happens, it just stays like that, unresponsive. I left it like this for like half an hour to see if it finally booted but it just stayed like that.
I tried pressing the exit button while turning it on to access the boot loader menu but with no luck, it does the same thing, all lights turned on and the display is completely blank, so I can’t run diagnostics nor I can update it via thumb drive.
Is there anything else left to try before bringing it to some repair center?
Thank you!