As I Understand after Windows 10 update the HP Pavilion won't boot,
Don't worry as I'll be glad to help you, although, to provide an accurate solution, I'll need a few more details to dissect your concern:
Let me get this straight, you've reseated the memory modules and also reinstalled the windows?
And yet the computer is stuck at the HP Logo? or do you mean that you couldn't get past the HP logo to perform the steps advised previously?
While I await your response, I have a few steps that should help:
Some HP Notebook PCs come with two sticks of memory and have two memory slots. If you experience a black screen or blue screen with HP logo, the problem could be with one of the sticks of memory or with one of the memory slots.
If the issue persists after the hard drive test mentioned on the same article I shared at the bottom of my previous post,
I recommend you remove the hard drive, start the computer without it and tap on the F10 to see if it enters the BIOS screen,
(if it does, it would prove a faulty hard drive, if it doesn't it would mean that the motherboard requires a replacement or repair)
Either way, you will need to Contact HP with the results of the last step I've suggested to set up a repair/replacement part order:
Please use the following link to create yourself a case number, then call and it may help speed up the call process: