iPhone 4 Constant Reboot WDT Reset Kernel Panic

[switch998]

I just purchased this phone from ebay and installed a new battery. The Gas_Gauge pin is not plugged in, so I don't know if that matters or not.

Anyway, the phone reboots every 5 minutes or so (only when fully booted into iOS). Here is the kernel panic log

Incident Identifier: XXXX
CrashReporter Key:   XXXXX
Hardware Model:      iPhone3,1
Date/Time:       2010-12-16 22:13:11.641 -0500
OS Version:      iPhone OS 4.2.1 (8C148)

Debugger message: WDT timeout
0s ago: 2000b50 2000r3ff000 1900m10004003 1800m0 1700m0 1600m0 1500m0 1400m0 1300m0 1200m0 1100m0 1000m0 900m0 800m0 800bff 800t3fe 700m0 600m0 500m0 400m0 300m0 200m0 100m0 0m0 
OS version: 8C148
Kernel version: Darwin Kernel Version 10.4.0: Wed Oct 20 20:14:45 PDT 2010; root:xnu-1504.58.28~3/RELEASE_ARM_S5L8930X
iBoot version: iBoot-931.71.16
secure boot?: YES
Paniclog version: 1
Epoch Time:        sec       usec
  Boot    : 0x4d0ad422 0x00000000
  Sleep   : 0x00000000 0x00000000
  Wake    : 0x00000000 0x00000000
  Calendar: 0x4d0ad512 0x0000222d

Task 0x811e8d3c: 6711 pages, 93 threads: pid 0: kernel_task
    thread 0xc0a42b20
        kernel backtrace: d2f8baf0
          lr: 0x80068a91  fp: 0xd2f8bb1c
          lr: 0x80068c95  fp: 0xd2f8bb30
          lr: 0x802dc217  fp: 0xd2f8bfa8
          lr: 0x800672fc  fp: 0x00000000

Task 0x811e8b58: 175 pages, 3 threads: pid 1: launchd
Task 0x811e85ac: 606 pages, 4 threads: pid 12: ptpd
Task 0x811e83c8: 181 pages, 4 threads: pid 13: syslogd
Task 0x83e9bd3c: 511 pages, 2 threads: pid 16: lockdownd
Task 0x83e9b974: 1955 pages, 29 threads: pid 18: mediaserverd
Task 0x83e9b790: 332 pages, 3 threads: pid 19: mediaremoted
Task 0x83e9b5ac: 315 pages, 3 threads: pid 20: mDNSResponder
Task 0x83e9b3c8: 898 pages, 9 threads: pid 21: locationd
Task 0x83e9b1e4: 410 pages, 2 threads: pid 22: imagent
Task 0x83e9b000: 399 pages, 1 threads: pid 23: fairplayd.N90
Task 0x83f1ad3c: 627 pages, 14 threads: pid 24: configd
Task 0x83f1a974: 212 pages, 2 threads: pid 26: accessoryd
Task 0x83f1a790: 4447 pages, 16 threads: pid 27: SpringBoard
Task 0x83f1a000: 669 pages, 10 threads: pid 31: CommCenter
Task 0x84053d3c: 348 pages, 3 threads: pid 32: BTServer
Task 0x84053b58: 122 pages, 2 threads: pid 33: notifyd
Task 0x811e81e4: 171 pages, 6 threads: pid 37: SCHelper
Task 0x83f1a1e4: 128 pages, 2 threads: pid 47: afcd
Task 0x83f1a3c8: 147 pages, 4 threads: pid 48: notification_pro
Task 0x893dfd3c: 326 pages, 3 threads: pid 51: apsd
Task 0x84053790: 211 pages, 3 threads: pid 52: lsd
Task 0x893df790: 1278 pages, 4 threads: pid 57: MobilePhone
Task 0x840531e4: 2411 pages, 6 threads: pid 64: MobileMusicPlaye
Task 0x811e8974: 2397 pages, 5 threads: pid 66: Preferences

Baseband logs show: "6:23:50 -0500 ST [rm] reset: reason=+XCGREG triggered dump;uptime=785;count="

Tried restore in DFU and in Restore Mode, but no luck. Any suggestions? I don't know whether or not to think it's hardware or software, since sometimes it will start to the connect to itunes screen with IMEI Unknown.