On our previous coach, a Forest River class C, which had a 16ft Dometic power awning they included a black strap about 8 to 10 feet long with a plastic rod about 4 inches long at one end. This strap is used to manually retract the awning if it should fail. The instructions were included in the awning's operating instructions. Google Dometic awning pull strap and you will see pictures of the strap.
As a note, check Dometic's website and the web for recall information on the Dometic Power Awnings. My awning deployed while travelling at 55mph on I95. It turns out that Dometic had recalled a series of awnings and the OEM (Forest River) could not track them back to the coaches they were installed on. Dometic did pay for the replacement awning and they did so in a very professional manner. My class C was out of commission for about 2 months but that was because there were no service centers that could work in the installation and side wall repair any sooner.
US Army (Ret)
2020 Entegra Accolade 37TS
2019 Jeep Grand Cherokee Trailhawk (Toad)
FMCA - F432054