HP DesignJet T610 won't recognize toner. Not able to update firmware. Now won't start properly

[tschadom]

Hey, this post is kind of my last resort.

A few months ago we (architectural students) got an old broken large format printer (DesignJet T610) for free. Otherwise we would't be able to afford a device like that, even though it's crucial for our work.
We wanted to challenge ourself in fixing it on our own. Again becauce of costs. The generous previous owner said to us, that only the carriage belt needs a replacement, that's just too much hustle for him. That's lot like changing a printhead. So we did that, with help of very comprehensive youtube tutorials. Successful it seems, because the print heads moved normally when the device was started. 

But then the black toner PK Toner was no longer recognized. The strange thing is, when booted the first time after the repair, everthing seemed fine. We were even able to send a printjob that started to process without any errors occurring.
Then it stopped and it said we need to reload the PK Toner, because it's empty.

Alright, we thought thats reasonable, because we got a fake old toner with the printer that seemed to be empty for real.
Ordered a new original HP one and put it in optimistically.
The printer won't recongnize it.  It says it's empty, which it is obviously not true, because it came fresh out of the box. The error now occurs right after booting the device. All the other toners are recognized.

I cleaned the contacts with alcohol and tried different toners.

Obviously first I thought thats because of our amateur repair job that we botched. But i don't understand how that should be possible, because in order to replace the belt you don't touch anything related to the toners. Where could we look at to troubleshoot any hardware problem?

I read somewhere that it could be a problem with the firmware of the printer, because it sat for so long.
I was unable to update it. The printer was not recognized by my windows 10 computer any longer, with the error clogging up the signal to the computer (at least thats my theory). Workaround? If there would just be a way to brute force the software. Even to ignore the toner error. Then we would just print without that faulty one.

Frustrated after the long repair job it now sat for another while.
Now when started, it just says that the printer needs to be restarted. Otherwise contact HP support. Yeah right. Try that.
I know, with all the fixing that's just not surprising. I would be bothered to take the thing apart again, maybe set the belt to a fresh start if we could sense any hope from you guys.
I know it seems like a lot and it's probably a hopeless case.
But it just seems like a shame if we just would throw that thing away, without trying out every last possibility

This is my last resort. Any tips, even just for one of the problems would be much appreciated.

If anyone from HP is reading this, please keep in mind that we are all possible future customers of a lucrative product of yours. The customer experience was not what we would wish for with a high end product like this designjet t610, even if we cancel out the bad situation we started out at.

Sry for any mistakes in my writing. English is not my first language.

[D Hook]

Your English is excellent.  No worries.

I think you guys are correct in trying to fix the printer.   Cleaning the contacts is a good start.  Get it working  right and they'll provide a long service life.  They're a real workhorse of a printer, IMHO.  Doing a belt change for the first time on one of these is quite an undertaking.  I doubt that anything you did during the belt change would have contributed to the problem you're having.  But you might want to take the end covers off and recheck anything you unplugged to be sure everything is tight.  (You can run this printer with both side covers removed if you need for trouble shooting.)

Couple things to try:

Shut the printer down from the front panel, then from the rear power switch.  Remove all the ink cartridges.  Then power up the printer without the inks inserted.  Once the machine boots, it will start asking for cartridges.  Replace them one at a time, starting from one end or the other and see if the problem cartridge still shows up as a problem.  Some times, the adjacent cartridge will actually cause the problem you describe.

Make sure all the cartridges are genuine HP.  Even if they're expired HP cartridges, I think they're better than the after-market cartridges.  The HP's are easily available on Ebay for very little money.  I know you said the PK one you bought is genuine HP but it's possible to get a bad factory cartridge too.

If the printer has been sitting a long time I would suggest replacing the printheads as well.  Again, Ebay is a good source.  But be aware all the ink cartridges must have enough ink in them to complete the printhead replacement process.  I think that's around 25% full.

If Repairtrooper comes to comment here, he's also a great source for knowledge and parts.  I believe he was a long time HP repair tech. 

It's best if you can leave the printer plugged in and the power switch on.  It will go into a sleep mode after a little bit and then every few hours it will wake up and do a self-test and a printhead sweep to keep them fresh.  Plus, when you need it it's ready to go without having to wait for the boot process from a cold start.  The biggest mistake people make with this model printer is that they do a complete shut down if they don't think they're going to use it for an extended amount of time.  The printheads dry up after awhile and causes problems with print quality.  I've had HP printers that I've used in my office that stayed on continuously  for 7-8 years straight and never a problem

I'm hoping others will post up some other trouble shooting tips to help you guys get the printer working again.   There's several diagnostic tests in the service manual to help pin point the problem.  You might end up having to do a reset of the EEROM to clear that error.  But don't try that until you've read over the service manual a bit.