Red Robin Shrub

We came back from holiday this week to find our 6ft Red Robin Shrub over 20 years old looks as if it is dying in part, across the centre area it looks as if something has been thrown over it and the leaves in a swath are dying It was very hot while we were away and someone was kindly watering the garden but nothing other than that Are Red Robin prone to suddenly dying the leaves are brown as if burnt but only in the centre the rest are growing well. Any ideas as to what could have affected it or what we should do now?