2008R2 SP3 Upgrade: Missing resource database.

I attempted to apply SP3 to a brand new SQL Server 2008R2 Enterprise instance.  The original instance WAS at SP2, CU12.

The installation of SP3 aborted and left the SQL Server service in an "updating" state (when viewed through config manager).

After a recommended reboot of the system, the SQL Service would not start.  I found in the error logs that the resource database files are missing.

Since this is the first instance I attempt to upgrade I don't have any reference on how this should have worked out.

The instance is a non-clustered virtual machine running Windows 2008R2.

 <Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
- <System>
  <Provider Name="MSSQLSERVER" /> 
  <EventID Qualifiers="49152">17207</EventID> 
  <Level>2</Level> 
  <Task>2</Task> 
  <Keywords>0x80000000000000</Keywords> 
  <TimeCreated SystemTime="2014-10-02T13:57:16.000000000Z" /> 
  <EventRecordID>6086</EventRecordID> 
  <Channel>Application</Channel> 
  <Computer>HSVSQLAPPREP02P.quaero.com</Computer> 
  <Security /> 
  </System>
- <EventData>
  <Data>FileMgr::StartLogFiles</Data> 
  <Data>2(The system cannot find the file specified.)</Data> 
  <Data>C:\Program Files\Microsoft SQL Server\MSSQL10_50.MSSQLSERVER\MSSQL\Binn\mssqlsystemresource.ldf</Data> 
  <Binary>374300001000000010000000480053005600530051004C004100500050005200450050003000320050000000070000006D00610073007400650072000000</Binary> 
  </EventData>
  </Event>

This SP has been out for about a week so it's doubtful I'm the first to do the upgrade.  I may be the first to do it from CU12.

Any thoughts on the root cause of this error?  Possible workarounds to bring the instance back online.

I have many instances that need to be upgraded, but not if it involves a ton of manipulations to apply the SP.

Thanks,