Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020
Cash flows from operating activities:
Net loss	$ (1,642)	$ (541)
Adjustments to reconcile net loss to net cash used in (provided by) operating activities:
Gain on forgiveness of PPP loan	(801)	0
Depreciation	47	46
Stock-based compensation	140	20
Change in fair value of warrant liabilities	0	(873)
Provision for doubtful accounts receivable	6	(12)
Provision for slow-moving and obsolete inventories	89	(78)
Provision for warranties	12	44
Amortization of loan discounts and origination fees	38	38
Changes in operating assets and liabilities (Sources / (Uses) of cash):
Accounts receivable	532	445
Inventories	(1,963)	1,546
Short-term deposits	12	(240)
Prepaid and other assets	4	53
Accounts payable	951	(152)
Accrued and other liabilities	(209)	222
Deferred revenue	1	(14)
Total adjustments	(1,141)	1,045
Net cash (used in) provided by operating activities	(2,783)	504
Cash flows from investing activities:
Acquisitions of property and equipment	(109)	(47)
Net cash used in investing activities	(109)	(47)
Cash flows from financing activities (Sources / (Uses) of cash):
Proceeds from the issuance of common stock and warrants	0	2,750
Proceeds from the exercise of warrants	527	0
Offering costs paid on the issuance of common stock and warrants	0	(474)	$ (510)
Principal payments under finance lease obligations	(1)	(1)
Common stock withheld in lieu of income tax withholding on vesting of restricted stock units	(2)	0
Payments on the Iliad Note	0	(226)
Net cash provided by financing activities	1,604	2,104
Net (decrease) increase in cash and restricted cash	(1,288)	2,561
Cash and restricted cash, beginning of period	2,178	692	692
Cash and restricted cash, end of period	890	3,253	2,178
Classification of cash and restricted cash:
Cash				$ 548	$ 1,836	$ 2,911
Restricted cash held in other assets				342		342
Cash and restricted cash	890	3,253	$ 692	$ 890	$ 2,178	$ 3,253
Austin Credit Facility
Cash flows from financing activities (Sources / (Uses) of cash):
Net proceeds from (payment on) credit line borrowings	0	55
Credit Facilities
Cash flows from financing activities (Sources / (Uses) of cash):
Net proceeds from (payment on) credit line borrowings	$ 1,080	$ 0