ti994ageek1970

I recently acquired a TRS-80 PC-2 Pocket Computer and cassette interface in good shape and it appears to be functioning correctly. The LCD screen works well and it appears to switch modes from PRO to RUN correctly. The computer also has an 8k expansion card in it and when I type MEM it typically reports that there is 24576 memory free. I am new to this line of pocket computers and have a few questions that I cant seem to resolve. Like I mentioned, the computer was reporting around 24576 memory but now only says 0. I have removed the batteries, push the reset button etc. but it continues to show 0 for memory and I do not know how to correct this or if I am just unaware of what to do? Also, even when it was showing the higher amount of memory available, I would switch to PRO mode to key in BASIC commands but it never seems to retain them. I would key in the line numbers with simple commands such as 10 PRINT "A" and then I would hit enter which should have placed the line in memory but it does not. I switch to RUN mode and type RUN but nothing happens. In PRO mode I try to use LIST or the up and down arrows to see the line numbers but nothing shows. Just curious if anyone can shed some light on these issues or have experienced them. Any comments are greatly appreciated.