never head of the back ram error. You may be talking abou a BACKUP RAM ERROR.
On a 2 slot, that is typically caused by a soda spill. Take a look under the cover, see if there is any corrosion of the area, or the board in general.
If there is, I do NOt recommend purchasing the board. For ANY board with such a problem, the bare minimum I would charge to repair would be $500, and I woukld not warranty the work. The problem is that the corrosion would still stay inside. Even if I spent 2 weeks repairing and rebuilding traces, there is still corrosion action internally.
If the board looks clean, check out the battery RAM. A loose pin or an actual bad RAM may do the trick. One quick way to tell the difference in the error, if the write/read is only a jnumber or two off such ads a read of 5554 or 55FF, that is either a single line or one of the rams itself failed. If a read which changes each time or comes up B240, then that is caused by corrosion and may not be fixable.