I had exact same problem as ProjectX reported except that my Ring to Tip voltage was 13.2V.  My troubleshooting results are provided below.  Is this sufficient to verify a board problem before I go to the trouble and down-time of returning the board for repair?  BTW, I'm almost certain that mine was lightning related.  This is the ONLY problem detected with the M1G but I had a gate controller fried as well as a couple of Insteon devices (all on different distribution panel but from same mains transformer.
Thanks,
jim
Test 1:
o	RJ45 connector at RJ31X CONNECTED
o	Global- Local and remote control ENABLED
o	Telco Seized light ON
o	LCD keypad user menu 8,6,4 Last onhook voltage= 0.0V
o	RJ31X: Voltage across #4 & #5 = 46.5V
o	RJ31X: Voltage across #1 & #8 = 13.2V
	
Test 2:
o	RJ45 connector at RJ31X DISCONNECTED
o	Global- Local and remote control ENABLED
o	Telco Seized light ON 
o	LCD keypad user menu 8,6,4 Last onhook voltage= 0.0V
o	Voltage across #4 & #5 = 46.5V
o	Voltage across #1 & #8 = 46.5V
	
Test 3: 
o	Outside Telephone line connected directly to Tip and Ring on M1
o	House phone connected directly to R1 and T1
o	Global- Local and remote control ENABLED
o	Telco Seized light remained ON before, during, after phone hookup
o	No dial tone on phone
o	Voltage across R1 and T1 = 13.2V