INCOME TAXES, Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
INCOME TAXES [Abstract]
Federal and state net operating loss carryforwards	$ 77,757	$ 81,526
Federal and state research credits	140	407
Interest expense limitations carryforwards	21,165	12,194
Transaction costs	778	882
Deferred revenue	434	480
Accrued expenses and other	1,148	1,236
Total gross deferred tax assets	101,422	96,725
Less: valuation allowance for deferred tax assets	(101,422)	(96,725)
Net deferred tax assets	$ 0	$ 0