Hi everyone,
I deleted the MBR of a 32GB usb key issuing the command: dd if=/dev/zero of=/dev/sda bs=512 count=1
I've backed up the data, so I can format the key, actually that's what I'm trying to do, but I can't write a new MBR because of I/O errors. For instance:
bash# install-mbr /dev/sda
install-mbr: Error reading /dev/sda: Input/output error
or
bash# dd if=/dev/sda of=/dev/null bs=512 count=1
dd: reading `/dev/sda': Input/output error
0+0 records in
0+0 records out
0 bytes (0 B) copied, 0.173344 s, 0.0 kB/s

Both writing and reading reports I/O errors.
I've tried several methods with no avail, does anyone has suggestions?

thanks folks

Btw, here's a dmesg excerpt:
[ 5.889124] scsi 5:0:0:0: Direct-Access Generic USB Flash Drive 1.00 PQ: 0 ANSI: 2
[ 5.910002] sd 5:0:0:0: [sda] 66488321 512-byte hardware sectors (34042 MB)
[ 5.912998] sd 5:0:0:0: [sda] Write Protect is off
[ 5.913011] sd 5:0:0:0: [sda] Mode Sense: 03 00 00 00
[ 5.913019] sd 5:0:0:0: [sda] Assuming drive cache: write through
[ 5.924990] sd 5:0:0:0: [sda] 66488321 512-byte hardware sectors (34042 MB)
[ 5.927998] sd 5:0:0:0: [sda] Write Protect is off
[ 5.928014] sd 5:0:0:0: [sda] Mode Sense: 03 00 00 00
[ 5.928021] sd 5:0:0:0: [sda] Assuming drive cache: write through
[ 5.928041] sda:<6>sd 5:0:0:0: [sda] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE,SUGGEST_OK
[ 5.981989] sd 5:0:0:0: [sda] Sense Key : Medium Error [current]
[ 5.982003] sd 5:0:0:0: [sda] Add. Sense: Cannot read medium - incompatible format
[ 5.982023] end_request: I/O error, dev sda, sector 0
[ 5.982031] printk: 221 messages suppressed.
[ 5.982039] Buffer I/O error on device sda, logical block 0
[ 5.982048] Buffer I/O error on device sda, logical block 1
[ 5.982055] Buffer I/O error on device sda, logical block 2
[ 5.982062] Buffer I/O error on device sda, logical block 3
[ 5.982069] Buffer I/O error on device sda, logical block 4
[ 5.982075] Buffer I/O error on device sda, logical block 5
[ 5.982082] Buffer I/O error on device sda, logical block 6
[ 5.982089] Buffer I/O error on device sda, logical block 7

...and here's the lsusb output:
Bus 001 Device 008: ID 1043:8012 iCreate Technologies Corp.
Device Descriptor:
bLength 18
bDescriptorType 1
bcdUSB 2.00
bDeviceClass 0 (Defined at Interface level)
bDeviceSubClass 0
bDeviceProtocol 0
bMaxPacketSize0 64
idVendor 0x1043 iCreate Technologies Corp.
idProduct 0x8012
bcdDevice 1.00
iManufacturer 1 Generic
iProduct 2 Flash Disk
iSerial 0
bNumConfigurations 1
Configuration Descriptor:
bLength 9
bDescriptorType 2
wTotalLength 32
bNumInterfaces 1
bConfigurationValue 1
iConfiguration 0
bmAttributes 0x80
(Bus Powered)
MaxPower 100mA
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 0
bNumEndpoints 2
bInterfaceClass 8 Mass Storage
bInterfaceSubClass 6 SCSI
bInterfaceProtocol 80 Bulk (Zip)
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x0040 1x 64 bytes
bInterval 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x02 EP 2 OUT
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x0040 1x 64 bytes
bInterval 0
Device Qualifier (for other device speed):
bLength 10
bDescriptorType 6
bcdUSB 2.00
bDeviceClass 0 (Defined at Interface level)
bDeviceSubClass 0
bDeviceProtocol 0
bMaxPacketSize0 64
bNumConfigurations 1
Device Status: 0x0000
(Bus Powered)

Thanks again