Blown HAI Keypad Fuse

Gents,
 
Need some help here... I was helping a friend with his Omni installation when he accidentally spiked the keypad data bus with high voltage (long story).  After a power cycle everything is back to normal except on the of the keypads, which is stuck on "NO CONTROLLER DATA".  The address is correct, and a spare keypad in its location and address works fine.
 
On the back of the keypad there is a fuse labeled Y1 that appears open by testing with a fluke.  The fuse only says 4.00 and what appears to be a CSA and UL symbol.
 
This is an HAI 11A03-1 keypad.  Does anyone happen to know the rating of this fuse?  A quick solder job will get it back into business.
 
Thanks!

Just a guess a 4 amps and a guess that it is an SMD fuse. 
 
I did the same with an Omnitouch 3.5 a few years ago. 
 
Same issue here with "no controller data" and it related to putting the VCC on putting the voltage on one of the serial wires. 
 
Think I posted about it here. 
 
 

Yeah, 4 amps at what, 24 volts?  125?  50?  Thats the question.

Yeah while that matters I do not think it matters much. 
 
IE from Littlefuse:
 
Can the fuse voltage exceed the application voltage?
 
Yes - Fuses are designed for use in circuits at any voltage as long as they don't exceed the fuse's maximum voltage rating. (Exception - medium-voltage fuses from 2,400 to 38,000 volts may only be used at the voltages designated on the fuse's label) The voltage rating of a fuse is a safety rating that should never be exceeded.

Four amps sounds awful high to me for a keypad.

A short is a short no matter what the voltage. We're not talking overload, but voltage going someplace where it shouldn't