Model 7393-27U - PC shut down in the middle of use last night and won't boot.
No beep codes initially.
Comes up to Lenovo screen with Phoenix bios logo in bottom right and Intel logo in top right.
Powers on and lights up.
Louder than normal fan sound that sounds like it's coming from processor fan.
Both processor fan and main fan at back of chassis are working when start with case open.
Get the 'System is starting..... to interrupt normal startup press Enter' screen.
Then get 'Network Broadcom NetXtreme Ethernet Boot Agent v 9.4.4
Ctrl-S to Enter Configuration Menu' screen.
Stops with large Lenovo logo and smaller Intel logo in top right and Phoenix logo in bottom right.
Got into BIOS and changed Startup - Power On Self Test to Enhanced,. Now get 1 short beep on startup.
Occassionally got memory errors in past when trying to shutdown.
Also didn't work correctly on KVM I was using so a shutdown actually caused a restart, Had to hold power buton for 10secs when started booting up again to shutdown.
So my question is have I lost the processor or hard drive?
Running some system diagnostics would be a starting point to try to isolate
Corrupt HDD image or Drive itself (less likely, but worth checking cables)
CPU - potential thermal problem
Enter BIOS and go into the Startup / Boot Order menu and ensure a hard drive listed. If not, check the cables, and look again. I've often seen drives not work because of a bad connection or cable. If it's possible try the drive in another PC. While a single beep is not a listed code in the Hardware Maintainance Manual. In cases with other systems, a more definitive beep code could be helpful in problem isolation
As a next step, download and create a bootable cd of Hitachi's Drive Fitness Test and use it to check the hard drive. It doesn't matter if your drive is not from Hitachi, it will still tell you if it's OK or broke. Other HDD test software could be used.
Ensure in BIOS that the cd/dvd drive is set to first boot device.
If the HDD tests OK - a potential next step would be to back up all data and perform a restore to factory default. Given the amount of time involved, this step might be defered to last.
Remove memory and try to run the system with a single memory module. If failure repeats, swap modules. If no difference, re-install the memory. In some cases, if the gold contacts show corrosion or appear dull, you can clean them by lightly rubbing them with a pencil eraser. Re-install the memory.
Run diagnostics on the system board.
Check the CPU. In the particular scenario above, this particular set of symptoms was caused by a broken clip on the CPU fan so there was separation between the processor and the fan on top of it. This caused the CPU to overheat in the time it took to startup and progress to the point in the boot sequence where it failed.