Bleed it and retry.
Loook under the boots (rubber bits on the ends) of the master and slave cylinders. if the area is wet then you need to rebuild the cylinders. cheap and cheerful - and not at all hard to do.
The other thing that you might have an issue with is ballooning of the flex line from the bulkhead to the slave cylinder. if it's well and truly perished sometimes these blow up rather than directing the hydraulic pressure where it should go. The multiple pump just provides more pressure to compensate for what the line lost.
Check the flex anyway the connections to them can leak.
ajr