Test and hold the test button to get the Phoenix menu.
MVC2 is not a CPS2 board, it's NAOMI. No suicide on NAOMI.
If that was a typo and you're still referring to how to tell if MVC is phoenix'ed, just like we said.
However, there are also decrypted roms out there that have no noticeable difference at boot. To be absolutely certain, you would have to pull the 03 rom and verify it against the native (non-phoenix/non-decrypted) game code rom set from MAME, with an EPROM programmer. If it fails against the native set rom, then test it against the phoenix set and the decrypted set.
Decrypted sets can be found here:
http://cps2.avalaunch.net/
:edit: to close the line of logic - if the rom verifies against the native code set, and the board runs with that rom inserted, then you are running on battery/encryption/native code. Encrypted code will not run once the battery dies and the encryption key is lost, as you probably know. Phoenix/decrypted code sets all require the replacement of rom 03 (but not necessarily all program roms).