I bought a couple of bonsai's
First: it's bonsai, not bonsai's.
The instructions we received stated to keep the watering tray full at all times, which we did
Are they in a pot in a tray,and is the soil touchihng the water? Bad advice.
it's looking like Charlie Brown's Christmas tree. The juniper was doing ok until recently when many of it's leaves and branches started to brown
Sounds like it is dying. I hope you are not keeping it indoors?
Do you have pictures?