Last November I got a 3" Japanese Juniper bonsai (my first). Over the
December holidays, it got a bit ignored and unwatered for about a week to a
week and a half. Now the leaves are rather crisp and some (maybe 5%) have
turned brown.

Your tree is dead. It may have been dead from being indoors even before the
holidays. Try again, but not with a juniper if you plan to kep it indoors.

Iris,
Central NY, Zone 5a, Sunset Zone 40
"If we see light at the end of the tunnel, It's the light of the oncoming
train."
Robert Lowell (1917-1977)