my broody hen was off her eggs for about 35 min, do you think the eggs are still alive? the eggs are about 18 days.
That won't kill them. In fact it is natural (Unless there was some other problem with the eggs.) I sometimes use an incubator and from day 8 until day 18 it gets turned off from 30 minutes to 2 hours (Once I forgot to turn it back on and it was off longer---no problem) every day. Once the eggs are in lockdown the incubator is kept on. Supposedly you have a higher hatch rate doing this. Hatch rate with my own eggs is near 100%.
A hen will leave her nest to eat. Usually towards the end when she can feel movement and hear peeping she'll sit tighter.