SMA SB 2800i - Manual (Page 24)

Device Description Operating Instructions
22 SMA Regelsysteme GmbH SB2800i-11:FE0504
Device Failure
When the failure occurs, the yellow LED is on for five seconds and
then starts the blinking code by staying off for three seconds and
then blinking five times in short intervals. The code is sent three
times.
If the failure persists, the signal starts from the beginning.
The Sunny Boy is in a state it cannot leave for normal operation.
Pressumably there is an internal failure in the device.
A qualified electrician has to examine the device.