This issue seems to crop up from time to time.
Traditional panels made with mono-crystaline or poly-crystaline solar cells are typically made with low iron tempered glass with breaks into small pieces as you noted. Typically ethylene-Vinyl acetate, (ETA) a type of plastic is layered on top of the glass, then the solar cells, then another layer of the ETA, and then a back layer of a different poly-flouro plastic such as Tedlar to give water and abrasion resistance to the back side. The whole thing is laminated together.
The problem is that the EVA is bonded to the glass, which is now broken into many smaller pieces. Removing the glass is at best a very slow and tedious process by all accounts I have read to date, and usually futile. For these types of solar panels, the glass is what gives most of the structural strength to the panel, and the embedded solar cells are easily broken within after the glass is shattered.
If the panel still outputs power, then one possible solution would be to place the panel upside down upon a flat and stable work space, and pour resin such as polyester resin on the back side to give the panel some rigidity, and then once that is set up, coating the front side with a thin coat of UV resistant clear epoxy to seal it up as best as possible. The results would be imperfect by might allow the user to get some useful life and benefit out of the panel.
If the Panel does not output any power, then likely one of more of the cells in series has cracked clean through, and I am afraid I have no good advice as to digging out the individual cells. You might try tapping the panel from the back to access the bus bars at various points and measuring voltage to determine where the break is and if there is only one you might be able to simply bypass that cell.
All in all it is a hefty amount of labor for a rather modest return in my opinion, but best of luck with project. Rich