This works. A great find in the all-knowing web. I had a problem where a RS would not upgrade to SP4 because the installer could not start the RS service. This link shows a way to fix it.
The SQL Server Reporting Services (MSSQLSERVER) service failed to start due to the following error: The service did not respond to the start or control request in a timely fashion
Quoting the original site:
Had an issue recently where we couldn’t get the “SQL Server Reporting Services (MSSQLSERVER)” service to start.
In the end it was quite a simple fix, we added the below registry key.
Open Reg Edit
Navigate to the following registry key “HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control”
Right-click Control, and create a new DWORD with the name “ServicesPipeTimeout”, and then press ENTER.
Right-click “ServicesPipeTimeout”, and then click Modify.
Select Decimal, and type 60000 (this will allow the service 1 minute to start)
This sorted it for us.