2.5 hours is nothing in the grand scheme especially inside an incubator that is insulating... There are times my incubator is easily open for an hour while I candle and monitor progress of developing eggs, and that is an open incubator, with no ill effects... The actual overall internal egg temp drop was probably less then a broody bird getting off a next to go get some food and water on an 70-80° day..
As you said the transporting them might have caused more damage, but honestly if you have ever watched the way broody birds handle, roll and knock eggs around I'm doubting you did much damage unless you really roughed them up...
My advice for the future is to invest in a small power converter, ones that can power a small incubator can be had for about $30, then power is only the nearest car or car battery away...
With a 20% off coupon you can get this one for $21, most small incubators are only 60-200 watts total if that, so this is plenty good... Most of the small foam incubators are surprisingly under 50 watts, even with the fan and turner...
http://www.harborfreight.com/automo...nuous-800-watt-peak-power-inverter-66814.html