I'm pretty experienced with electrical.  Did you design this yourself? and I really am not a huge fan of coding and really involved things on computers but I can learn if its needed.  and I prefer wiring the least amount of things to my board as possible.  but mine fail.. it stays at room temp.

Did you check it with a meter for resistance?  You could also unplug the pad from the board and put 12 volts across it to see if it indeed has failed.  As far as my bed heater goes I guess you could say I designed it myself.  Although I am sure I am not the first person to do something like this.  There really isn't a lot  to it as far as changing firmware.  I use the same thermistor to measure the temp but doing the PID auto tune on the bed can't be done in EEPROM like for the hot end.  However if you managed to make that firmware change (Max Temp for Hot end) Than you can figure this out.  It has to be tuned because it is so powerful that it will way over shoot the temp.  The main reason I went this route was to decrease the load on the board and power supply.  This way the only load is the relay itself and the load of the bed heater is carried by the wall outlet.

After a month I've had some problems.  1. Cannot Hit "Home" because when I do it keeps trying to push into the corner on the right and will not stop until i unplug the printer.  2.  Today for some reason my print bed will not heat up.  and stays at 20 degrees.  If there is a upgraded bed I can buy I'll buy it and wire it myself like the E3D Hotend.  3.  I purchased Taulman's 645 filament and love it.  but if I'm printing anything over an hour and I'm not there to help, it will get stuck and mess up the print.  It wont stay on the roll and tangles like crazy.  and i have no way to put it like the other filaments because the roll is smaller.  Also if anyone recommends any other upgrades to my printer.  I'd be happy to know.....Thanks!

Try the individual 'home' buttons for each axis and determine if it is the X or Y axis then trip the switch by hand when 'homing' to see if the switches are actually working... if they are working then the fix is easy just put a couple layers of tape on the switch lever or the part that hits it, this is a fairly common issue with SD printers because of how the switches are mounted. If the switches do not stop the print head when tripping them manually then check the connections on the main board for the limits and if you have a multimeter test the actual switches by unpluging thm at the main board and checking for continuity at the plug while tripping the switch.

There are a few aftermarket beds out there, some of them will usually require a bigger power supply to work well...

http://www.soliforum.com/topic/1819/hea … isonsstls/

http://www.soliforum.com/topic/2544/my- … eated-bed/