I'm in UK and have two dead boards in my Antminer S9, I'm thinking about buying a hot-air surface-mount rework station at about £1,000 just to change the easily obtainable power components in the hope that it's not the circuitry under the security glue that's faulty. If you have several more bad S9 boards and I can break a couple of them perfecting the fix process then PM me.

Not quite sure we're talking about the same kit though as you say 550 MHz and mine are about 4 THash per board.