HTC Desire 816 wedged-ideas please?

So I pull out my phone one day and the keypad is locked. Nothing I do (short of a hard reset-which I don't want to do because I'll loose a lot of valuable info) seems to bring it to life. After pressing lots of key combos I managed to get it into safe mode, but now it is totally frozen. Plugging it into my PC and trying to do a back up reports device not available. Does not recognize the OTG connection.

Is there *anything* I can try to wake this thing up??? I am an experienced hw and sw designer so familiar/proficient with hw implementation and code development, so no suggestion is beyond my capability, so pls any suggestion is appreciated. I am not familiar with the android development environments but have used many (probably similar) tools in the past.

One thing I am curios about is if this phone has any hardware ports on it such as jtag, i2c, that I can plug into in hopes of unwedging it?


My experience also tells me that if something is frozen sometimes the only recourse is a hard reset....but, are there any tricks to try and recover lost data that are worth trying? ( no, I haven't backed up the phone recently and that is on me).

thanks for taking the time to read/consider this problem

-John