LG G5 Promotion Site Link: http://www.lg.com/us/mobile-phones/g5/promo/carrier-selector
Many other users have posted online today since the LG G5 rebate site went live that they are getting an “IMEI number is invalid. (1)” when trying to submit their promotion info.
I was having the same issue and then remembered that some phones used to show a MEID number that is 1 digit shorter (on the last digit) than the IMEI. I deleted the LAST number of my IMEI number from the entry and it worked! I just wanted to share this in case someone else was having the same issue. Here’s my confirmation email!