联想打印机,M3120 ,出现close the back cover,back cover open!

联想打印机,M3120 ,出现close the back cover,back cover open! 出现back cover open close the back cover. 兄弟出现back cover open close the back cover. 打印机上的 back cover open close the back cover 是什么意思呀 我的联想3220一体机提示Back cover open close the back cover.如题 复印机故障显示 back cover open close the back cover m7020联想打印机出现以下提示:cover is open close the front cover请问是什么意思, 兄弟7010开机滴滴的响、出现Back cover open close the Back cover是怎么回事? 联想传真机M3120复印时提示 Cover is Open Close the Front Cover 是什么意思 Back cover open ciose the Back cover 打印机型号：兄弟FAX-2820.不能打印 显示close the back cover open ,可是后盖是关好的 联想(lenovo M3120)打印机显示：Dust on Drum.Open the front Cover and