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The hard pedal and red warning light are telling you there is no pressure in the system - usually caused by the pump not running. If the pump is running continuously the relay isn't the problem and the accumulator won't prevent the pump from building pressure even if it is bad. Once all the fluid is drained out of the pump it can be really hard to get the air out. Here are instructions for getting the air out. -> How To Purge Air From The Brake Pump If the instructions don't work for you, you might have to rig up a hand vacuum pump to connect to where the steel pressure line connects, then suck the air out of the pump. Also, check to make sure fluid is getting to the pump through the line coming from the reservoir.

The pump itself is generally reliable as long as it remains full of fluid. There are no actual seals on the inside of the pump except two small semi-flexible cups inside the rotor that act as the pump. The pump is a piston pump that spins very rapidly inside an eccentric housing with a ball bearing running against the inside of the housing which moves the piston cup to pump the fluid. It is a very poor air pump and it needs the weight of the fluid to help flinge the pistons outwards in their bore to press against the eccentric. In other words, they may get stuck if the pump is dry, but applying vacuum to the outlet may help if the standard bleeding operation doesn't work. The pump is high pressure but low flow. It can take upwards of a minute or more to fill a good accumulator from empty to 2600psi cut out pressure. The standard accumulator only holds 1/4 liter so the pump only produces about 250cc/min, or about 8.5 fl/oz.