Uwatec compatable transmitter battery replacement

[Leo53214]

I recently bought a used Air Z with transmitter. The transmitter's battery is dead so I took it apart to change the battery and it turns out it is "Uwatec compatable" but not Uwatec. The inside is filled with some sort of oil and the battery is a Inorganic Lithium size 2/3AA 3.6volt. Not at all what I expected.

Since it is not a genuine Uwatec I'm guessing Uwatec would not do a battery replacement. Any ideas?

Thanks, Leo