Suggest you use a chemical stripper to remove the remains of the old finish and then some dilute bleach to remove the staining. You may not be able to get the veneer back to its original colour, but strip past the stained bit so that you can see what the original colour is. It will almost certainly be darker than the damaged section, so that will need staining to blend in. I use Colron woodstains and sometimes have to experiment with mixes of colour to get a good match. I have found the best final finish is Ronseal Interior Satin which ends up very close to the original Bavaria finish.