If you have fully depreciated all your assets and have no cash in the bank, your total assets would be zero. It's possible you have "loans from shareholders" in the asset portion of the balance sheet due to the balance due on one of the assets. If this is the case, then your capital (equity) balance would be zero. Capital accounts cannot be negative.
Example of Schedule L:
Assets
$2,000 Capital Assets
($2,000) Depreciation on Assets
$2,000 Loans from Shareholders
Total Assets = $2,000
Liabilities
$2,000 Short term loan for capital asset purchase
Members Equity
$0
Total Liabilities and Members Equity = $2,000