With the info provided an exact answer can't be given, but:
As mentioned by dextorb, The black boxes are normal for a non-initialised display, and his advice to use a 5k pot instead so you can trim the contrast is good (advised in the LMB204BDC datasheet too)
Damage - I think your display is very likely to be okay if you had a 5k resistor between +5V and V0.
Of course make sure you (double) check all connections (voltages, datalines signals, etc) carefully.
If all looks okay, but only black boxes are seen, I think the most likely thing is the display is just not initialised properly. Checking the datasheet it uses a ST7066U controller. Read through the ST7066U datasheet and make sure you are following the initialisation procedure (examples start on p.23) correctly. If using some library check what controllers it works with, and/or look at the initialisation function to compare with datasheet advice.
Sometimes these controllers can be pretty sensitive to timings, so make sure you follow the instructions as closely as possible (e.g. where it says things like "wait > 50us", "wait > 1ms", etc)