What's the Name of That Book??? discussion

I read this book around 5-6 years ago, about a group of kids who discover a machine of some sort that allows travel to an alternate dimension or world. This is linked in some way to their parents, and the ending depicts them in another world (possibly stranded) where they find out their parents are considered criminals (I think on a wanted poster?)
It was one of a series and I read it in a (possibly hardcover?) copy with a light blue/turquoise cover. I think there was a bunch of additional stuff (like bookmarks etc.) with it and I do think something about the author struck me, though I cannot for the life of me remember what it was!

the cover doesn't match but
The Strangers by Margaret Peterson Haddix, first book in The Greystone Secrets.
This was only published in 2019 though, so might not be it.

Nope. The Strangers has come up a lot when I've searched but it's not the book I'm looking for.

bump :-)

Found it!!
It's A Mutiny in Time by James Dashner !!!
I apparently misremembered the cover because it shows up as deep red!
I also seemed to remember a connection with the 39 steps - Dashner wrote those as well !!