I have this old Sanyo AM/FM Radio Cassette recorder that is not working. I think I bought it in the late 1990's and used it to listen to tapes or radio for several years. It always worked fine.

I came across it recently and it had 4 old AA batteries still in it.
Probably had been in there for years. I removed all of them and put in 4 new AA batteries. (Made sure they were put in correctly) However, after trying to hear the radio and putting in a cassette tape, nothing happened. The little light that normally comes on did not light up and radio and cassette player would not work. I tried 4 other batteries - still nothing.
I looked closely where the batteries go inside the compartment and found there was some greenish color on the ends where the batteries go. Perhaps it just needs to be cleaned in the battery compartment real well but I don't know what to use to clean them. I don't want to get too much moisture in there so just wondering if anyone knows what would be the best way to clean our the green substance (probably leakage from the old batteries that were in there for so long.)
Thank you.