1) For deworm-ing,
Use Panacur for deworm. Apply once and repeat after 2 weeks, if continues, repeat the treatment. Alternatively, you can visit the vet like Dr Terry Yu.
2) Use recovery for forcefeed, daily apply until it starts to eat again.
Indotestudo elongata should be easy to keep. Even no heating equipment during winter in HK, it should be ok but make sure that it is kept indoor.