B777 is the only type I can think of with a pneumatic starter (in addition to electric).
Are there others? A380 perhaps?
A380 has no pneumatic starter. No other aircraft I know of has one.
Have there been many (any?) total electrical power failures that haven't been caused by loss of the engines too? I can't think of any.
Only major failure when all power was lost on B787 was in the Loerdo incident, when there was a total loss of power and the RAT deployed. As they were on approach at that time they continued in that condition. Details of that incident are sketchy. There was a major fire in the central Electronics bay, where all power panels are located. I don't think NTSB got involved as the aircraft was still in the test phase. The reason for the power loss and fire according to Boeing was FOD !!!
Then there was the United incident and diversion to New Orleans, where power loss from one Gen was not properly restored from the other good generators. When you have 6 Gens loss of one Gen should be a piece of cake. Again the details are sketchy.
The same problem occurred again on a new Qatar B787 after delivery flight. The details are once again limited. the out burst of it's Chairman against Boeing is well documented.
Boeing has mentioned that these problems are now sorted out.
During my time in aviation there were some incidents of total power loss on different aircraft, but did not result in any accident. In one instance the aircraft was B777 that was dispatched with one gen inoperative, and other side engine failed for an unconnected reason. But as the APU was already running, power was automatically restored.
One remarkable incident was on a A300-600, belonging to a charter airline, that was positioning to an MRO. It was dispatched with one Gen inoperative from far east and when over India the other Gen also failed. The flight continued all the way to France with just APU. It was a ferry with just 2 crew. Still it was remarkable that the crew had faith on the APU for 6-7 hours. When I met the crew after landing, both Mexican, I had to tell them that they were bravest crew I have ever met to have faith in the APU for 7 hours.
On airbus there is detector called Avionic smoke Detector, which can trigger a warning (Most instance false), the crew have to kill most of the power and land ASAP. This has happened several times, a recent one is on Air Canada 320 at Edmonton.
Incident: Air Canada A320 near Edmonton on Aug 18th 2012, avionics smoke indication