If the batteries have leaked and the chemicals are inside the remote, get a new one.
If the connections are corroded very bad, get a new remote.
If the connections are a bit corroded, they can be cleaned with a Q-tip and 99% alcohol. Clean the contact face with emery cloth (Fine).
If the remote still does not work, get a new one.
If you need the code list, here is the
URC7781 manual (UK)If this is A US model, please provice your URC model number for your remote or look on
One-for-all website.