Do you have a fireplace? You are describing a dead Juniper, as an evergreen it won't come back, some of it may be saved but I doubt it. The classic mistake of most is to take a plant/tree that needs a dormant period in winter and break that. It made one year which is better than most would do so it 'was' pretty healthy to begin with. It would have done much better under a shrub in the yard covered with a layer of pine park or needles (up to the top of the pot). What it didn't need was water and fertilizer while being dormant, the roots have been destroyed. You could try sticking it back in the ground for a while and see what happens.

Alright so I only have figured out how to post photos in reply so here goes, I hope this helps more. The OP photo is taken today, I open that window to let the sun shine on it on sunny afternoons but it's only a south facing window and it's somewhat filtered because it's going through a screen, so I try to gently take it out to get direct sun occasionally on mild mornings or early evenings. This photo below is what it looked like the day it arrived at my house, as you can see it had some brown needles from day 1, but I didn't consider that a problem, I didn't consider they would have sent me a plant that was already sick.

Oh dear... make yourself a promise first, to never go by tags stuck on plants because they're usually one size fits all, which means your tree's tag applied to lots of trees but not yours! Junipers do NOT like getting watered often at all, and submersion for 2 days drowned it. When junipers get hard and break off, they're gone... but it may have been on its way long before you came along anyway as they go on looking green for ages after death. Next time you think a bonsai is cute, come here or to books, etc. first and find out if you have the right growing conditions for that tree, and what you need to do from the day it goes home with you. As far as bugs go, Safer's Insecticidal Soap Spray may have helped, but you can't know that for sure now. And don't fuss because we've all been there many times - it takes a while before you know what to do.

It's actually more important for deciduous material than evergreens because deciduous plants enter dormancy and then pass into a period of quiescence, during which any prolonged exposure to temps much above 42* can initiate growth. Pots & soil are passive solar collectors, so even if the air temp is 0*, if there is sun on the pot or soil the soil temp in the pot can rise above 42* during the day. During winter thaws, this can be a serious problem, because once the plant is stimulated to growth, the plant is significantly less able to resist chill injury when temps drop. Also, sun tends to increase transpirational water loss from foliage, which can be a serious issue if water in the soil is unavailable as ice. Plants on the north side of buildings are shielded from the sun, so the added transpirational water loss and passive solar gain (soil temps) are non issues. Actually, I prefer that my evergreens over-winter in the garage. Foliage never dries out, and since the temperature rarely drops much below 30* (unless someone forgets to close the OH door at night) I never lose even the finer roots. Al