CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (87,126,000)	$ (98,714,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,547,000	1,422,000
Loss on sale of property and equipment, net	59,000	0
Noncash lease expense relating to operating lease right-of-use assets	1,406,000	1,338,000
Impairment of long-lived assets	9,988,000	0
Gain from early termination of right-of-use assets	(35,000)	0
Inventory write-downs, net of scrapped inventory	7,712,000	675,000
Loss on advances to suppliers	1,385,000	0
Change in fair value of convertible note and warrant liabilities	858,000	14,000
Realized loss on instrument-specific credit risk	46,000	0
Stock-based compensation	18,071,000	23,959,000
Convertible note issuance costs	0	474,000
Realized losses on redemptions of marketable securities	0	77,000
Amortization of premiums and accretion of discounts on marketable securities, net of change in accrued interest	(211,000)	1,086,000
Expected credit losses	35,000	0
Changes in operating assets and liabilities:
Accounts receivable, net	451,000	3,605,000
Inventories, current and noncurrent, net	(2,459,000)	(2,634,000)
Prepaid and other current assets	2,279,000	(1,130,000)
Other noncurrent assets	284,000	527,000
Accounts payable	252,000	839,000
Accrued expenses and other current liabilities	(3,135,000)	85,000
Operating lease liabilities	(1,528,000)	(1,341,000)
Contract liabilities	(987,000)	(1,931,000)
Other noncurrent liabilities	383,000	0
Net cash used in operating activities	(50,725,000)	(71,649,000)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment	(1,951,000)	(4,200,000)
Proceeds from sale of property and equipment	283,000	0
Proceeds from redemptions and maturities of marketable securities	76,350,000	96,592,000
Purchases of marketable securities	(19,331,000)	(23,929,000)
Net cash provided by investing activities	55,351,000	68,463,000
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from exercise of stock options	455,000	1,174,000
Proceeds from the issuance of convertible notes	0	9,850,000
Payments for convertible note redemptions	(6,235,000)	(874,000)
Payment of 2022 convertible note issuance costs	0	(324,000)
Taxes paid related to the net share settlement of equity awards	(1,445,000)	(4,621,000)
Proceeds from issuance of common stock under the Common Stock Purchase Agreement	136,000	2,891,000
Stock issuance costs related to the Common Stock Purchase Agreement	(3,000)	(29,000)
Proceeds from issuance of common stock through the Employee Stock Purchase Plan	334,000	0
Net cash (used in) provided by financing activities	(6,758,000)	8,067,000
NET (DECREASE) INCREASE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH	(2,132,000)	4,881,000
CASH, CASH EQUIVALENTS AND RESTRICTED CASH—Beginning of period	21,214,000	16,333,000
CASH, CASH EQUIVALENTS AND RESTRICTED CASH—End of period	19,082,000	21,214,000
SUPPLEMENTAL CASH FLOW INFORMATION:
Cash paid for interest	115,000	133,000
Cash paid for income taxes	16,000	20,000
SUPPLEMENTAL DISCLOSURE OF NONCASH INVESTING AND FINANCING ACTIVITIES:
Purchases of property and equipment included in accounts payable and accrued liabilities	0	28,000
Operating lease right-of-use assets obtained in exchange for lease obligations upon adoption of ASC 842	0	556,000
Operating lease liabilities extinguished upon early lease termination	335,000	0
Conversion of convertible notes and accrued interest into Class A common stock	3,338,000	600,000
Taxes related to net share settlement of equity awards included in accrued liabilities	0	4,000
Operating lease right-of-use assets obtained in exchange for lease obligations upon adoption of ASC 842
SUPPLEMENTAL DISCLOSURE OF NONCASH INVESTING AND FINANCING ACTIVITIES:
Operating lease right-of-use assets obtained in exchange for lease obligations upon adoption of ASC 842	$ 0	$ 16,284,000