HP 39gs Self Test
Individual tests can be performed by simultaneously pressing the ON key and the F4 key (the fourth key on the top row). Software build information is briefly displayed, then a test menu is displayed.
8.IRDA (Send & Receive)
A.AUTOTEST (Merry-Go-Round, till battery is flat).
Simultaneously press ON and F3 (the third key on the top row) to exit test mode.