This is a PCB heated bed I assume? The only real way to get a flat print surface if the PCB is out of whack is to clamp something stiff on top of it. I have found that glass often isn't stiff enough (at least when it's ~3mm or less thick) and will flex enough to make printing difficult if the PCB underneath is significantly warped.
Your best option would be to pick up a new heated bed from a reputable supplier if you can afford it. Don't get just get the cheapest one you can find on eBay, they can be really hit-and-miss as to quality, and in some cases won't work at all without modification.
