frog croaking, but not coming out?

my frog Burger has been buried since October. i’ve insulated his tank and his humidity is kept around 80% or 60% most of the time, but he still hasn’t come up. the warm side of his tank gets up to mid 80s (Fahrenheit) and the cool side to 73. i’ve tried digging him up to feed him, but he’s never interested and just goes back underground. recently he’s been croaking every few days. is this a good sign? is there anything i can do to make him come out? i’m worried about him