This is not accurate, and the inaccuracy is the difference between solvency and liquidity.
If svb had longer (ie weeks), they still wouldn't be able to cover their debts. Its not a matter of needing time to arrange buyers for their assets; their inability to pay isn't related to liquidity today or tomorrow, it's related to their asset's value. If they snapped their fingers and marked to market all their assets, they would be in debt because they're insolvent.