I still have one of the 32GB developer units from when HP was trying to entice people to write for it. I ran Cyanogen and Evervolv on it for a while. It will,

I still have one of the 32GB developer units from when HP was trying to entice people to write for it. I ran Cyanogen and Evervolv on it for a while. It will, with a bit of fiddling, run Nougat (see https://forum.xda-developers.com/hp-touchpad https://forum.xda-developers.com/hp-touchpad) but the various pieces of the support tools, ex. novacomm, are decrepit and compiling them on current Linux and toolchain didn't result in a working tool so you have to bodge around with old binary releases. Given how slow the device feels with Marshmallow and then Nougat, I will probably save my pennies for a newer tablet. As to not booting, they're really hard to brick. They can however run down so that even the battery icon won't show. Try charging it using the original charger or other that can do 2A for a day or two then attempt a hard reset.