See other posts about the same situation. Healthy trees will put more leaves out to replace the ones that died. If they don't leaf out again, you should invoke the warranty.

Keep them watered without drowning them. If there is no sign of life after a month, then they are probably dead. Lightly scratch the bark on a couple of branches in about a week - if it is green under the surface, then the tree is alive and will probably make it. If it's brown, then that branch is more than likely dead. If most branches are dead, or you don't think it has enough live area to recover - use the warranty.

...and put lots of mulch down, that will help even out the temperature.

there is NO REASON TO BE WATERING EVERY DAY in zone 5 ... at this time ...

you may kill them with too much love...

do not water them again until the soil feels dry at 3 to 6 inches ... insert finger and find out ...

you probably .. maybe ... who really knows .. but your finger.. wont need to water again until mid to late June, depending on how water moves through your soil ... and how hot it gets and how fast it does so ... and whether or not you properly mulched them ....

good luck

ken

PS: of course, i also said it never gets this cold in zone 5 in April ... lol ....