I always look for the simplest answer first.
This MAY be the problem: you reinserted one or more of the batteries with the wrong orientation. Typically, they will connect in series to produce a higher voltage than a single battery by itself.
For example, an AA battery puts out about 1.5 Volts, and two AA's in series would produce about 3 Volts, with the positive of one battery connecting to the negative end of the other; the negative of the first and the positive of the second connect to the remote's terminals. The connection between the two batteries is usually in the battery holder in the remote, and the batteries will be physically oriented in opposite directions. For example:
Of course, something inside the remote may have broken instead, but double-check the battery connections first.