I purchased an AVH-X1700s and had the same thing happen. I went to do the update and it was running version 8.40..??? Now I have an AVH-X3700bhs that's glitching. Power cycles off and on, screen and buttons freeze. I'd like to try to update it to 8.40 but I can't find it anywhere.
I've googled "pioneer firmware 8.40" and it's installed in similar models. Avh-x2750, 3750, 4750. Etc. These models do not have SiriusXM as they are not sold in North America???? That's all I've been able to come up with.
I don't use Sirius so I'm still interested in trying 8.40 in my 3700.