Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 2,379	$ 4,459
Restricted cash	100	100
Accounts and other receivables (net of allowance for doubtful accounts of $458 and $804, respectively)	1,566	1,659
Inventory	3,467	3,741
Prepaid expenses and other current assets	383	337
Total current assets	7,895	10,296
Property and equipment, net	54	60
Operating lease right-of-use assets	226	250
Deferred tax asset, net	27	28
Other assets	29	29
Total assets	8,231	10,663
Current liabilities:
Accounts payable	1,314	1,689
Accrued and other liabilities	1,930	1,814
Warranty liability, current	163	163
Operating lease liabilities, current	112	111
Total current liabilities	3,519	3,777
Operating lease liabilities, noncurrent	127	151
Common stock warrant liability	51	72
Total liabilities	3,697	4,000
Commitments and contingencies (Note 10)
Stockholders' equity:
Common stock, $0.001 par value; 300,000,000 shares authorized at March 31, 2024 and December 31, 2023; 23,457,090 and 23,457,047 shares issued and outstanding at March 31, 2024 and December 31, 2023, respectively	23	23
Additional paid-in capital	642,374	642,302
Accumulated deficit	(637,767)	(635,574)
Accumulated other comprehensive loss	(96)	(88)
Total stockholders' equity	4,534	6,663
Total liabilities and stockholders' equity	8,231	10,663
Series C convertible preferred stock
Stockholders' equity:
Preferred stock, 10,000,000 shares authorized: Series C convertible preferred stock, $0.001 par value; 95,388 shares issued and outstanding at March 31, 2024 and December 31, 2023