+1 to almost everything already posted, especially the "Don't dump the beer" sentiment.
In order to fix a low mash temp and keep some maltiness, run a small decoction. Grab a couple of quarts of the mash, grains and all, and boil it. Yup, boil it. Stir constantly, as scorching can be an issue. After 10-25 minutes (the longer the better), add the decocted portion back to the mash tun. Stir well.
In order to fix a low mash temp and keep some maltiness, run a small decoction. Grab a couple of quarts of the mash, grains and all, and boil it. Yup, boil it. Stir constantly, as scorching can be an issue. After 10-25 minutes (the longer the better), add the decocted portion back to the mash tun. Stir well.