I think a Byzantine revival is actually possible in 1402, with this scenario. Byzantium was blessed with three good Paleologus rulers during this period OTL, but the Ottomans were too strong to resist at that point. Before he became Emperor, Constantine managed to conquer the small Latin remnants and make a lot of progress against the Slavs. He was only driven back by the Turks. Supposing the Turks weren't around to stop him, he might have restored the European territory of Byzantium to something like its 1300 borders.
However, the Ottoman army must be annihilated entirely by Timur for this to be feasible. Remember, during this time, Western Anatolia's population was still very Greek, even if the ruling class had been replaced by the Turks. If you have a situation where Turkish power is balkanized and the surviving Emirs fight each other instead of getting organized again, I could see the Byzantines making inroads into the area.
In other words with three good rulers, a complete Ottoman collapse and infighting amont the Turk remnant states, a Byzantine revival is still possible, though this would be a ressurection of Byzantium around 1270 - 1300. The borders of Basil II's Empire, or even that of Manuel's Empire, are simply unrealistic in the extreme. At best, and this might even be ASB, you'd have a restoration of 1204 Byzantium, just before the 4th crusade destroyed it... the coastal fringes of and western regions of Anatolia plus most of the southern balkans. The interior was far too assimilated by the Turkish population to ever go back to Byzantium. The last opportunity for that was squandered by Manuel in 1176.
However, all of that depends on a scenario where all Ottoman princes and the majority of the army are killed by Timur, and the European base of power falls.