回複：It is not your fault at all.

From what you wrote, especially the two were laid off before you were hired, the application was chaos. The manager must be under high pressure to have the application fixed so he is expecting a magician and this is the reason he paid you so high. The reality is that you cannot get familiar with a complex application in so short time. I can tell you that the manager will be laid off soon. The same story happened on me before. I was doing a mission impossible at that time and missed the release. I quitted after four months. My company hired people twice to backfill my position. One quitted after two month and another quitted after one month. Finally the project manager and director all quitted (or laid off).