Support Website Problem: Won't accept valid printer serial number, can't proceed to get support!

[DKLxxx]

I'm trying to reach support online. It first asks me for my serial number, which I have located and entered. It only tells me that the serial number is invalid. I have reconfirmed the following: Valid 10-digit serial number, label readable, no confusion over 0 or O, L or 1, nothing mistyped.

The printer is an Hp LaserJet Pro 400, MFP M475DW, Product Number CE864A.

I believe there's a blown fuse or power module. No reaction to on/off button. Dead in the water.

A) How can I enter my $&#@! serial number and; 

B) Is there any way to fix this thing?

[Valsimot]

Online support is 0 help in your case. On older printers when you enter s/n you get invalid, even if you manage somehow to pass that glitch online support for out of warranty printers isn't something.

You have 2 options for repair, one is to get it somewhere to repair, or if you are handy with tools repair by yourself.    The 3rd option is the worst recycling.

It's possible to get an service manual online that is the first step for the repair.