A:Answer If I read your question correctly, you know this monitor should last for '5 years of use'. You bought one but didn't use it for some time, and now you've begun using it and wonder if the estimate of '5 years of use' includes the time it was stored.
You're specifically wondering because it doesn't seem to be working correctly. Based on your description, I think you should probably be more concerned about the 2-year Warranty for Parts & Labor. (Which, I'm fairly certain, starts from the purchase date, whether you use it or not.)
I realize this is a year old, but I'm answering because it might help someone else. There isn't much you can do, but hopefully you put new batteries in. If it was stored with batteries in it, the contacts might need to be gently cleaned, as well. Next, check the air tube for kinks or 'flat' areas. If it was stored with too much weight/pressure on the air tube or cuff, that could cause problems. Then, if there wasn't a cap/cover on the air tube port, look to see if anything got inside, or if it looks damaged.
Once you've done & checked those things, definitely contact Omron about any ongoing problems.