So, Soviet engineers took out some of the equipment inside the spacesuit. However, in the process of doing this they accidently unhooked the wiring to a pressure gauge and a temperature gauge.
This caused a short circuit of the whole system, which had to be fixed before the flight was given a Go for launch.
Please read April 6, 2011 The Guardian article 'How Yuri Gagarin's historic flight was nearly grounded,' which goes into more details on the problems plaguing Gagarin and his flight team on the hours leading up to his flight into space.
The former top-secret documents that contain these newly revealed problems before Gagarin's flight (and other information) are expected to be publicly released on April 12, 2011, on the fiftieth anniversary on Yuri Gagarin's flight into space and back to Earth.
This information and more are contained in the Russian book called 'The First Manned Flight.'