Why doesn’t VSphere show VMWare Tools as installed

The electrical storm could have resulted in any number of issues. Depending on the class/quality of your data center's facility, there could have been an impact.

• Your most useful logs would be visible in the vSphere Client "Events" tab.
• Do you have any out-of-band management available? DRAC, perhaps? That would give you information about the physical hardware status.
• Is this actually a Dell server? Which model/generation? If so, you should install Dell's CIM agents for ESXi 5.
• Does your PERC/5i controller have cache memory and a battery-backed cache unit (BBWC)? Running without those can impact write performance.
• An individual VMWare ESXi system does not have any automatic update capabilities.
• You should install VMWare tools on your guest systems.
• Do you have dual power supplies in the server and access to an A/B power feed? If this is a single-PSU system, that's a possible culprit.

I was just going to advise the OSP option, but the real fix is probably upgrading your ESXi host to the current revision/patch level. As of this writing, your build number is 1065491, and the current is 1483097.

VMware Tools often get incremented in the ESXi patch releases. It makes sense to keep your hosts up to date.