One thing to keep in mind is to be patient. It can and may take days for the battery to charge up enough for the TP to wake up. If and when it does, plug it into the the standard TP barrel charger and let it sit until it reaches 100% before you play with it. If it is truly freshly out of the box, you will need to bypass activation as the HP servers are no longer out there.
Follow this thread for the process
Activation Bypass for TouchPad
If you want to totally bypass webOS ( but why would you want to? Just kidding!), there is of course Android or if you are adventurous, LuneOS which is android based OpenWebOS that has been in development for some time and has made great progress.
If you go webOS, there are a LOT of free archived apps available that you can install that still work well or at least reasonably well, (notably the USA Today app still works!) plus plenty of games that work fine. Plus you will want to install preware and a few other things, but one thing at a time.
If after a week you still do not have any luck, it is possible the battery is too far gone to be revived. I found one where it was pretty swollen. There are replacements out there, but you will need to open up the TP and that is a bit of a challenge if you have never done it before.
If it comes up, you will have a durable tablet that even after 6 years is still quite viable.