Russia Left Without Access to ISS Following Structure Collapse During Thursday's Launch (nasaspaceflight.com)
When the rocket launched, a pressure difference was created between the space under the rocket, where gases from running engines are discharged, and the nook where the [144-ton] maintenance cabin was located. The resulting pressure difference pulled the service cabin out of the nook and threw it into the flame trench, where it fell upside down from a height of 20 m. Photos of the accident showed significant damage to the maintenance cabin, which, according to experts, is too extensive to allow for repairs. The only way to resume launches from Site 31/6 is to install a spare maintenance cabin or construct a new one.
Despite the fact that the fallen structure was manufactured in the 1960s, two similar service cabins were manufactured recently at the Tyazhmash heavy-engineering plant in Syzran for other Soyuz launch complexes at the Guiana Space Center and Vostochny Cosmodrome. The production of each cabin took around two years to complete, however, it was not for an emergency situation.
"Various experts gave different possible estimates of the recovery time of the Site 31 launch complex: from several months to three years."