Console interface problem on the switch

I have build the LAB for my BCMSN and used 3 3550 switches. Another Cisco 2511 was an Terminal server. It just works fine for yesterday, but today I find problems. There was some poor connction of power cables so the switches are powered off and on couple of times. After that one of them still alive, but two others with problem. One just shows all the port LEDs on and doesnt start at all (connecting with HyperTerminal - nothing on the screen) and the second one starts well, shows all the logs on the screen, but when I;m trying to type anything - it doesnt gois in, like problem just with the input intrface (output just fine, it shows all the messages of switch, like ports on/off, messages about STP, Links etc).
For the first bad switch I have try to change the Power Adapter but nothing happened.
Second bad switch I have try to boot in ROMMON (by the front-panel button) and try to type anything - again no any letter on the screen, not recognizing Enter, back-space, just nothing. Thinking about the changing IC MAX3387E, but before that would like to confirm if any help.