No bootup/post on CRT ? HUM. Possible video card/CRT) problem? should give something on the CRT (Flashing cursor - if the video card/CRT is good) or MB/CPU has checked out for good. Unplug all but esentials monitor, floppy, and keyboard and see if you get lots of beeps and video (anything would help). Would not hurt to have a bootable floppy in the floppy drive, if it boots all plugged in items are eliminated.
One at a time add components until crash/no-post and you should have identified the problem component. Logical (step-by-step) trouble shooting is the only way to quickly isolate a problem.
BTW - For me it was a steaming HD (that could not be identified by the PC as a computer component) that stopped my system as you describe.