Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Current assets
Cash and cash equivalents	$ 5,837	$ 13,766
Accounts receivable, net of allowances of $0 and $0, respectively	1,079	476
Costs and estimated earnings in excess of billings on uncompleted contracts	0	987
Inventory	192	1,109
Other current assets	729	1,311
Total current assets	7,837	17,649
Property and equipment, net	1,849	2,993
Operating lease right-of-use asset	1,308	0
Restricted cash	435	435
Intangible assets	221	486
Other assets	186	1,470
Total assets	11,836	23,033
Current liabilities
Accounts payable	1,871	2,411
Accrued liabilities	2,045	5,602
Deferred revenue	21	0
Contract liabilities	9,755	0
Other current liabilities	83	10,154
Current portion of operating lease liability	656	0
Current portion of finance lease obligations	25	21
Total current liabilities	14,456	18,188
Operating lease liability, net of current portion	1,348	0
Finance lease obligations, net of current portion	9	33
Deferred rent, net of current portion	0	695
Total liabilities	15,813	18,916
Commitments and contingencies (Note 12)
Shareholders' equity (deficit)
Preferred stock, par value $0.001; 25,000 shares authorized; zero and zero shares issued and outstanding	0	0
Common stock, par value $0.001; 150,000 shares authorized; 125,803 and 100,105 shares issued and outstanding at December 31, 2019 and 2018, respectively	126	100
Additional paid-in capital	568,496	550,133
Accumulated deficit	(572,599)	(546,116)
Total shareholders' equity (deficit)	(3,977)	4,117
Total liabilities and shareholders' equity (deficit)	11,836	23,033
Reconciliation of cash, cash equivalents, and restricted cash balances
Cash and cash equivalents	5,837	13,766
Restricted cash	435	435
Cash, cash equivalents, and restricted cash	$ 6,272	$ 14,201