Hi all: i did the calibration and it told me that unable to calibrate the gauge failed in cycle2. now i need to change them. but i get off my battery. i pull out 3 nails. but can not get out the battery back. the 3 naails that i used were in the front, under the thumb keys. any ideas on how to get out the batteries? thanks so much Ramy moustafa saber licturer at: faculty of musical education music arranger and sound engineer Sent from my iPhone