Remote does not work after

this is a generic answer that applies to many multi unit remotes

Many remotes have to be trained. the user manual contains a list of code series that identify to the remote what equipment the remote is intended to control. changing batteries may erase the prom that this information is recorded in.
From either the printed manual or by looking up the manufacturers web site from descriptive labels on or in the remote, you can determine the (usually) 3 digit code for your tv dvd video audio units and the button that begins programming mode sop that you can press the unit button, enter the code, press the button to confirm. and be done

My specific remote requires

Hold [menu] untill the red lamp flashes 3 times
press [dvd]
enter the code on the number pad
press [dvd]
press [tv]
enter the code on the number pad
press [tv]
press [vcr]
enter the code on the number pad
press [vcr]
press [audio]
enter the code on the number pad
press [audio]
press [aux]
enter the code on the number pad
press [aux]
press [menu]

thankfully the remote recharges on the dvd player, and I only did that once