need help with Z450 printer

[Mathias]

Hello, we just got an used Z450 printer. it most likely havent been used for some years now, just standing.
There have been loads of errors and we have overcome most of them so far, but now we're stuck.

It keeps saying errror 1003, cant read printhead HP11.

we tried cleaning the printhead, pogo pins, printcard. replaceing the HP11 with a brand new one.
But this error just keeps on comming.
Any idea what we should try?

Thanks in advance

[curious aardvark]

check the wires. Sounds like a broken connection.

[Mathias]

How do i check them?
Just checked all the wires i could find for a loose connection and wasnt able to find any.