Yes you can indeed open them. You risk ruining the contents though. If you have a dremel tool, use a cut-off wheel and place the wheel directly under the push button where you see the crease between the top and bottom. The latch is only about 1-1.5 inches within the crevice of the lids. Due to it's unique design, the safe must be compromised if you don't contact sentry. If you want to do it a quick way, wear a gas mask and use a plasma cutter on the rear crevice, this will cut into the hinges. You will have to force it open with a pry bar afterwards as the exterior surfaces may melt together.
If you do care about the safe, contact the company.
There is no way of opening a sentry safe without a combination code. If you lost your combination and you need a new combination, you will need to contact sentry safe?s customer care team by sending them a notarized letter confirming that you are the owner of the safe. For more information, log on to www.sentrysafe.com/CustomerCare/Lost_Your_Combination.